Since there constantly are these questions about which heroes are good, should be kept or summoned for and which ones to feed away and generally hate on, here´s what I think about all the 3* heroes in the game. WARNING: This is going to be long (even for my standards). If you read all the way through, you get a pat on the back and probably a headache.
If you find a hero I missed let me know and I´ll add him to the list somewhere (probably towards the bottom). Let´s see how many I forgot :D.
Generally speaking there is no reason to keep copies of heroes, I will mention the few exceptions to this rule with the relevant heroes. If nothing is mentioned, delete the copies.
If you don´t know any of the abbreviations I use, check the foot note, if I forgot to add one, let me know, so I can add it there.
A few general points, before we get to the heroes.
Costumes: Since this is aimed at newer players I assume you got the hero with the costumes (assuming you started playing after the costume came out and you therefore got the costume along with the hero). The only exception would be the S1 heroes which you get left and right without costumes. Simply lower the category by 1 if you don´t have the toon costume, hopefully you will get it soon (keys for costume summons are rather easily available, even for FTPs). So for example if I say Bane is good (assuming the toon), then the original without costumes would be OK quality. Easy enough right?
Note: ALWAYS max all costumes if you max a hero. For the CB. Then you can decide which version you like best. And LB that version (well after you LB the original first of course). Often these days the difference isn´t too big between versions, but some of the older costumes can be significantly different…
As a rule of thumb: If it´s a toon, it´s probably good 
Not entirely true of course, a few still suck, but the best stats (by double CB) and the toon passive immunity (to DD/DoT/Mana control) are a big bonus that can easily move heroes up into a category it would otherwise not reach. It certainly is the reason why the biggest number of strong 3* heroes is found in the costume chamber. Which is also why the costume chamber is recommended for summoning for newer players.
In the description I will not talk about the originals, they are simply weaker versions of the toons, but I do mention the C1s, if they serve a function besides the CB.
Also certain heroes (that generate buffs for your own team) become stronger with toons around them, because the buffs cannot be removed reliably from toons.
6TR means “6 tiles rush”, so you can charge these heroes in 6 tiles (2 matches of 3) during rush settings, which is obviously a huge advantage over all other heroes that charge in 7 tiles during rush. 6 tiles is reached by 9% mana boost, which usually means 5% CB and 4% class talent. Many of these are toons!
Superior talents are improved versions of the regular talents and only exist in classic heroes (= toons!). Especially strong is the Superior Wizard talent, watch out for it in heroes! These heroes can dispel every time they deal damage, which includes tile damage! Other exceptional superior talents include Fighters (for the high revive rate and mana on revive), Rogues (for evading damage) and Paladins (10% heal on damage). Monks (resisting all ailments) and Clerics (resisting mana control) are useful classes in general (especially good on defense) and more so in the superior version. Druids have their special niche in bloody battle (extra minions). Sorcerer, Barbarians and Rangers are less useful talents than the others, but still not useless.
I decided to use 4 categories to classify all heroes: Within the color in each category, the heroes are sorted alphabetically, not ranked.
Must-haves (MH!): Call them MVPs if you prefer. The point is: They are the best in the game. If you get one, max it, no need to think about it much. Worth investing your resources into both getting and maxing them, so save up your summoning coins, aethers etc specifically for these heroes.
Good: Heroes that are generally useful. You may not need all of them, so feel free to pick and choose, where multiple heroes fill the same role. But you won´t go wrong with any of them. You get one, you got lucky!
OK: Heroes that have the occasional use. If you have a big roster with many of the higher classed heroes, you can most likely feed most of these away (save the occasional niche hero). If you have a small roster and few options, these may simply be the best you have available and then they will do just fine, so don´t be afraid to work on these if that is what you got.
Garbage: Heroes that have no use at all. Even with small rosters it´s probably not worth investing resources here. Better to feed them away and not waste roster space. Even duplicates of other heroes would be more useful than these. Of course unless you absolutely have nothing else at all.
1. Must have (MH):
Blue:
Dawn: Those mana stealing minions are a pain to deal with. The only thing keeping her down is the toon passive (resist mana steal) and her arch nemesis Kvasir. Can even be used in rush wars!
Gunnar: The C1 (DD+spirit link) is the most important part of the blue event teams. Can be used in other color teams like the red one as a 4-1 instead of mono and can also be used in 4* even 5* if no other spirit link hero is available.
Joukahainen: (EHT!) Best dispeller in 3* world, with additional buff block, best counter for Shrubbear in rush. MH for both rush and buff booster.
Karil: The standard damage hero in the standard event team. May have 2 or even 3 copies in that team. Can be used in tourneys as well, but beware the low def stats.
Nordri: blue EDD, essential part of the blue event team, but also very often the blue EDD hero for titan teams (added benefit of being a Barbarian). For Mythic titans even multiple copies would be useful. And of course can be used in tourney damage stacks as well.
Yao: The alternative to C2Karil. Slightly better in tourneys (dispelling minnion), slightly worse in the event teams (slower animation). I would rather max 1 Yao and 1 Karil than 2 Karils or 2 Yaos, but you do you…
Green:
Faiez: Original and Costume are very similar and both absolute MH in rush. Having the costume makes both versions better by making the passive hit 100%. Useful even in buff booster. Can be used in rush wars (left wing) against Alfrike tanks.
Shrubbear: Alpha taunt! The only 3star taunter. Rush MH. (with Zarel becomes 6TR). Another great option against Alfrike tanks in rush wars! Being slow not as great outside rush.
Zarel: the only 3star Bard. The 5% bard bonus can make all other heroes with 5% CB or a 4% mana talent into a 6TR. But she also has a good hit and other effects, so she´s a real rush MVP! The bard bonus has less significance in normal speed settings and she´s slow, so in regular speed she´s not that amazing.
Zarola: Strong fast hit-3 (see Alessia one category down). Zarola is stronger in 3* events (bosses don´t have mana, so her damage is maxed out) and she is much easier to get (with EHT in Valentines season) than Alessia. 2 or even 3 copies are in a green event team variant, but they can also make up a tourney damage stack together.
Red:
Bagreg: EDD is super rare in 3* only 2 colors exist, this makes a red event team very strong, even though the standard is blue.
Boots: DD partner for Bagreg, both in event teams or in tourney attack stacks. After these 2 any red hit3 hero will do nice damage.
Buster: One of the top 3 3* heroes. MH for titans (and if you think about Mythic Titans you may want to max multiples), MH for 3* and even 4* events (making the blue event team a 4-1 with him in the later levels when the damage otherwise is too low). Amazing for rush (and potentially bloody battle) tourneys. Absolutely save EHTs for him!
Purple:
Treevil: Not as crazy anymore as he used to be, but still a MH for rush.
Yellow:
Bertulf: If no other normal attack option is available, then he´s the one to use on titans! Most people get either him or Wu Kong as first titan damage hero. Either works.
Felton: Good sniper, Strong musketeer family and buff reflect on the enemy.
Jolly: Another rush MH. Both on offense (makes everybody 6TR) and defense strong. Can counteract a lot of treevils nastiness etc. (EHT!)
Kvasir: An absolute MH for bloody battle. One of the heroes where the original is better than the costume (preventing minions is more essential than preventing buffs, but of course if you need a pseudo healer in a buff booster tourney, why not?).
2. Good:
Blue:
Helo: Best blue healer
Planchet: One of the best blue snipers (and there are many who will instead be called garbage) with Musketeer family and self heal.
Swan Maiden: Highest TP for a 3*, which is important for tourneys, if you want to play for top 100 ranks. Also a strong set of skills, but I never find space for her as I have so many other blues… Definitely a pain to play against.
Ulmer: The C1 (6TR) is a part of the standard event team, but can be replaced by another hitter (or Buster). The toon is a Superior Wizard. Near MH.
Valen: good sniper, DD, Superior Fighter.
Green:
Alessia: Strong fast hit-3 (see Zarola 1 category up)
Belith: 6TR Top notch healer with dispel, the C1 has a niche use in buff booster tourneys. Near MH.
Berden: good sniper.
Brienne: 6TR Strong tank in buff booster tourneys (especially if undispellable with toons/green heroes on the team), The C1 is the strongest DD among all green heroes, so is a good choice for titans.
Carver: A baby – Li Xiu (which is a top notch 4* tank), so an option for tank position.
Dölgöön: Very good supporter, especially in buff booster tourneys (6 tile double buff), but can also counteract sniper damage on offense in bloody battles or be a defensive tank. Also part of the occasional green event team with DD+spirit link on charge 2.
Fianna: Absolute monster in Bloody battle. Those growing Fiends are plain unfair if you can´t remove them
General Yin: Very strong option for dispel in rush.
Goopy: Good hero (EHT!), but there are so many good green hitters in 3* it´s hard to find him best at anything.
Gramps: The only 3* reviver, so the uniqueness gets him classed highly. Personally I am not a fan and never use him.
Grevle: Attack boost and overheal make him a nice combo if you like to bring a healer on events or maybe for a buff booster tourney. Or just plain old PvE. Also my wifes favourite hero, so I try to emulate the body shape…
Jing: My preferred green sniper. The additional counterattack minion is great for bloody battle especially.
Mnesseus: Fast dispel and cleanse on the C. Toolbox hero.
Noril: Used to be the best green hitter, many people used multiples of him (including myself), nowadays only good in combination with Maeve for the family bonus. Still a good hero, but not the MH anymore he used to be. Zarola wipes the floor with him.
Roxia: Interesting hero for tourneys, that doesn´t seem to be used very much. Maybe because there are so many other strong greens?
Red:
Azar: The C1 does steal mana from 3, the toon is the sniper version.
Ei-Dun: good option for mana control (the updated version of the old classic Bauchan)
Fawn: Interesting fast support hero with mana speedup and dodge.
Hawkmoon: Strong C1 for buff booster (double buffs with HoT) and rush (6TR), while the attack boost would be most interesting in event teams. Outside of tourneys/events, the toon is probably stronger, but how often or for how long do you use 3* heroes outside?
Jahangir: 6TR, one of the better red, slow, hit-all heroes.
Rufus: Good partner for Jahangir with DD to all.
Starswift: Good damage, good partner for Boots.
Purple:
Aderyn: One of two purple healers. If you got both pick the one you like better and get rid of the other. Aqueela: fast dodge is good for buff booster and bloody battle tourneys. Original is a Rogue, but Costume is 6TR.
Balthazar: Probably best sniper in 3* world. High damage and SuperWizard. Great wing on def. Counter to Shrubbear. Near MH.
Greel: A rush monster, best to follow 1 or 2 Treevils to clean up.
Maeve: Not the MH anymore she used to be, but DD never gets old, so she´s still good especially in Buff booster (2 stacks) and rush of course and with her partner Noril (green) for the family bonus. Also the 44%DD is rather on the high side, so might be an option for titan DD.
Para: One of two purple healers. With additional Attack down and easy to get with EHT, so often the first choice for purple healer.
Renfeld: The C1 is the interesting version for the mana control. The toon not so much.
Tyrum: Dispel and on the C1 cleanse. Toolbox hero.
Yellow: (lots of healer options!)
Bane: 6TR sniper, partial treevil counter
Edelaide: A fast healer with an additional gamble effect. She is much underestimated IMO. Can be used on defense, but also against titans, if other options to boost normal attack are missing.
Gan Ju: 6TR sniper, partial treevil counter
Jaco: Fast hit3 plus mana steal. Good combination and my personal favorite in the yellow damage department.
Kinsaishi: Another option for hitter, this one in Ninja form.
Melia: Crit (buff booster? titan use?) and Blind on the C (bloody battle?) give you options for various formats.
Paeia: Very strong in rush! Designed to counteract Treevil.
Pixie: Counter for treevil, but the horrible old stats…
Poppy: Strong fast shooter.
Rekhetre: HoT overheal as usually especially interesting in buff booster. Waiting for the costume to shine again, a bit behind other healers right now.
Ribbit: A very good option for avg speed damage (with mana steal and extra DoT)
Rustbeak: HoT + dodge + crit but only for 3, so limited to defense tank position, but killer in buff booster!
Saskia: heal + dodge + delayed HoT is a very strong combo. At fast speed this might be the best yellow 3* healer for both offense and defense.
3. OK:
Blue:
Chick Jr.: EHT. Used to be good, but got overtaken by newer hitters.
Gato: Ailment immunity (a rare skill) nearby
Frosty: Healer+Minions
Green:
Featherino: Cute Owl! Damage requires maxed out stats, so if you feel like LB2+25 I would elevate him to “good”
Gnomer: Very fast sniper is an option for a defense wing. Otherwise not strong enough.
Isstak: The C1 has DD, the toon is good for some damage.
William: New stats and a starting mega minion is good for bloody battles, but even better options exist.
Yona: Good effects but you can´t plan on getting what you need. For the RNG fans only.
Red:
Bauchan: Got replaced with C Ei-Dun.
Dante: Interesting idea, but the damage isn´t enough. Otherwise could play a 6-tile team with Kornel 
Kornel: Interesting support hero (buff booster?), but no damage or heal.
Nashgar: OK sniper
Phoenicus: OK support and possible use in specialized event teams, but not for regular players.
Rudolph: Mana steal
Skrekok: Too old to still be considered good these days.
Sudri: Used to be a monster on rush defs, but worse things have pushed him out.
Waqas: Actually not bad, but there are many options for slow, red, hit-all and he isn´t top of those right now. May change again when he gets his costume (and potentially 6TR?).
Purple:
Betty. New stats, but nothing special.
Björn. I like him, but never use him anymore these days.
Gill-Ra: The original is like a weak version of treevil, the C is the opposite. Dispel/Cleanse is nice, but in purple available on the faster Tyrum for example.
Morganite: Ninja, should be better. But if you´re a speed freak maybe?
Yellow:
Candy: too many better options for healer in yellow.
Cedar: CMelia seems more verssatile.
Dolrak: The only yellow DD hero in 3*. Yellow in general has few DD options, so if you have no other yellow DD hero, this guy may be your man for the titans. Otherwise not much use.
Kailani: The C1 (6TR) has a big attack boost, the toon can be an option for tank, especially between other toons/healers.
Sally: In rush still a good option for big damage output in yellow (to kill treevil), otherwise not so much.
4. Garbage:
Blue:
Graymane: Hahaha
Guardian Lemur: No reason to max unless he´s your only blue healer.
Jarif: might get moved to OK, when his costume comes out
Jarvur: weak sniper
Soroca: weak sniper
Vodnik: weak sniper
Virgil: just not good enough to make an interesting concept actually useful.
Green:
By-Ulf (Triple buffs make him show up as buff booster tank, well it did a long time ago)
Friar Tuck: Can´t imagine a worse hero.
Hisan. Compare to the good ones.
Muggy. Basically he has no skill at all.
Whacker. Used to pack the biggest punch when he came out. Not anymore. Better than most other garbage, but in green, competition is just too high.
Red:
Basil: Maybe tank in a no-blue-buffbooster def surrounded by toons? Not really worth it just for that though
Li: worst slow red hit-all option
Namahage: too old, was OK before, even good when he was released 107 years ago.
Squire Wabbit: Used to be a big damage dealer, but times have moved on.
Vollermork: Below horrible garbage, needs a category lower than that.
Purple:
An-Windr: Don´t remember what he does, but every time I read the skill, I remember, why I don´t bother remembering.
Budatin: Go visit your buddy Vollermork in the trash can!
Chochin. Used to be more interesting in the early days with the mana slow, but there are better options now.
Edd: Compare to Balthazar.
Guardian Bat: Too old nowadays.
Jack: Compare to Balthazar.
Morris: Hilarious! I love mine, played him in 1-hero-cleans in war (so I could say he mana stopped the entire defense). Funniest hero in the game! I bet some intern created him. But no matter how much I love him, I can´t call him good (or even OK).
Oberon: crappy toon!
Prisca: the S1 is my idea of worst hero in the game. The toon makes her able to look over the edge of the trash can she lives in, but not enough to make her leave it.
Vlad: Compare to Balthazar.
Yellow:
Agnes: There was something special about her stats (don´t remember what lol). Also her family bonus makes me sometimes use her (unlevelled), because I get mana when she dies. Together with an unlevelled Gulli and an unlevelled Gulli costume I get 60% mana when all 3 die which means I can charge the other 2 heroes in 6 tiles lol. It´s called suicide squad. And no I don´t recommend trying that at home
Arman: Same as An-Windr.
Dawa: The meme of uselessness.
If you are interested in 3 star Dragons: Check this guide instead:
Abbreviations:
EHT - Epic Hero token
DD – Defense Down
EDD – Elemental Defense Down
DoT – Damage over time
HoT – Heal over time
LB – Limit break
C - Costume
CB – Costume Bonus (stats and 5% mana boost)
C1 – First Costume
C2 – Second Costume
C3 – you get it…
toon – Toon Costume (which is C2 for 3* heroes)
Here´s another recent thread on 3* heroes focused on which ones to get rid of
https://forum.smallgiantgames.com/t/ruskins-3-star-hero-removal-service-may-2024/345891?u=gargon
