You have an amazing roster, and I definitely wouldn’t call it bloated, but maybe a little overwhelming with so many heroes that need leveling. I’ll throw you some advice/counsel, but it’s your decision whether you wanna take it or not:
First, I would focus on building up a few rainbow teams of 4* first. 4* have better stats than 5* up until 5* reach 4T, so most will benefit you more than 5* will (aside from the really good 5* with unique or beneficial specials, then I’d make an exception). Plus, 4* are much cheaper and quicker to level, and take a lot less unfarmable mats than 5* do. You can max two 4* for the price of one 5*.
After you get a few 4* leveled in each color is when I’d consider starting on your 3* to help fill out your roster for war and to let you compete in the beginner tier of the challenge event. They’re super fast and cheap. If you don’t care much for the beginner tier though, you could continue with a few more 4*, dupes, or start on your 5*.
Usually, I would wait to work on 5* til you’re close to having all of the necessary mats to take them to 80. If their specials are beneficial, or if you run out of other good heroes to work on, are the two exceptions I would make to leveling them earlier than usual. Maxed 4* can be used to complete everything in game too, so I’d highly recommend getting a few in each color to max first. Then you’ll be ready to get some more of those 5* in the works.
Also, I would focus on one hero in each color at a time. Throwing feeders around to too many mouths at one time can slow your progress down significantly. I would suggest working on one hero in each color at a time until their either 1. Maxed or 2. At the mat wall. I would stick to on-color feedings while doing that as well, since that gives you the most exp per feeder.
As a rule of thumb, I would always keep your last copy of every 4* and 5* hero due to rarity. I would also keep one copy of all of the good 3* to participate in the event. Dupe 3* are only necessary if you’re lacking in a color, or you plan to eventually compete in the beginner tier. Dupe 4* and 5* however, are worth keeping if they’re good. Though, if you do a lot of pulls, I would keep about one or two dupes of limited time heroes and 5*; the regular 4* you’ll be able to get back through TC20 or pulls. If you don’t do many pulls though, then I’d keep them all just in case, with a max of maybe three dupes.
It’s fairly cheap, in the grand scheme of things, to expand your hero roster. I would highly recommend it; especially if you’re considering eating a few heroes that you think you may one day use just to have more space. It costs less than a summons, and never goes away or disappoints you. Probably one of the best gem investments in this game.
4* That Deserve Your Attention:
Red: Wilbur, Boldtusk, Falcon, Lancelot and Scarlett (for high attack stats)
Blue: Grimm, Kiril (Sonya and Triton if you pull them)
Green: Buddy, Caedmon, Melendor, Gadeirus (for a buff in green), Little John (high attack stat), and maybe Kashhrek (if you need more healers for war/an amazing tank in the low plat range)
Yellow: Wu Kong and Chao for mana control (Li Xiu would also be worth it too)
Purple: Merlin (Tibs, Rigard and Sabina if you pull them)
3* Worth Keeping and Leveling:
Red: Nashgar, Hawkmoon, Namahage, Rudolph
Blue: Valen, Ulmer, Gunnar, Gato
Green: Belith, Brienne, Berden and Mnesseus
Yellow: Bane, Gan Ju, Kailani and Melia
Purple: Balthazar, Tyrum, Gill-Ra and Chochin
Your Top 5* That Deserve Mats:
Red: Zimkitha for that fast cleanse and buff, and Marjana for a fast sniper- one of those two first. Azlar is great for his DOT and attack stat, so he’d be next (in my book), after Zim and Marj. Elena also has a nice high attack stat. Khagan, well, yeah no.
Blue: Isarnia’s lowering defense ability is amazing, and Magni is an amazing sniper that raises defense, and Misandra could be nice for the mana gain and fast sniper- so it’s between those three. Aegir, idk about him. Thorne, not so much.
Green: Morgan is actually pretty good, but there are just so many more amazing greens, so idk if I’d take her to 80 unless she’s your only green 5* for awhile.
Yellow: Joon is an amazing sniper, and Vivica is the best healer, so one of those two depending on what you need (sniper or healer). Justice is an alright tank, but I’d do the first two over her. Guardian Owl, meh.
Purple: Guardian Panther is amazing, but she does need other purples to maximize her potential, and that’s where Merlin being maxed could be a huge help. Her dispel will still be useful, so she deserves to be maxed. Victor is also very good with his very fast mana and defense buff (and high attack stat), so I’d put him second probably. Quintus can be last.
For maxing your first 5*, I would pick the most versatile heroes out of the bunch, since they’ll be your only 80s for some time. Obviously, you should ascend whoever fills the role that best fits your priorities (ex. Titans, raids, events, etc.) and build your team around that. You don’t want to run all utility heroes, or all snipers. Mix and match to build the most effective team, that has a solid synergy going on.
Like I said earlier, I would focus on maxing at least the first couple of 4* I listed before working on more 5*. First though, I’d finish off all your heroes at 3T to 70 to maximize their damage output, but then after, start on those 4* til they’re maxed or at the mat wall. Those 4* at 4/70 will be stronger than your 5* at 3/70.