I’ll start… in no particular order…
I realize I left healers off, so I’ll give special mention to Rigard. He’s a beast.
Mine are (with caveat that I am only listing those from my stable)
Boldtusk
Kiril
Triton
Caedmon
Merlin
These are probably faves rather than “best”, but it’s all pretty subjective
Honourable Mention to Gormek, I love that big boofhead, he sure can take a hit
Keeping the Rainbow in mind…
Wu
Grimm
Wilbur
Caedmon
Tiburtus
Of course, everyone should have Rigard and Melendor as subs because, well, they’re healers.
Best on my team:
Wu Kong
Wilbur
Buddy
Guardian Jackal
Merlin
Subject
Best 4* heroes
Wu Kong- best 4* Glass Nuke
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Rigard- best defensive 4* healer
Melendor- best offensive 4* healer
Grimm- most versatile Ramming Pulverizer trio
Hansel- best special defense, single target mana control 4* hero
And a close sixth
Guardian Jackal- Best 4* Super Glass cannon (with bonus Elemental yellow defense debuff )
boldtusk boral hu tao sabrina sumitro
i just love boral let the enemy kill em self 
My G. Jackal has gotten me my best titan score, even though he’s only 3/60 right now.
Sabina, because she was the first deep healer that i pulled and she debuffs the enemy of all sorts of nasty things i dont want sent at me.
Triton, nice little sniper with the added heal bonus
Wilbur, i send him into war battles where I’m under powered and i stay alive long enough to be victorious!
Kiril, his nice little buff on titans means i don’t need to spend a lot of banners!
I’m currently leveling up lots of different other 4* heros. Getting a 6 team roster of them at 3/60 before i start those pesky 5* . So this may definitely change in say 6 months!
Just gonna speak about the heroes I got or use/used :
I know that some others are generaly very helpful like Grimm, Gormek, Tiburtus for example.
Wilbur
Jackal
Wu
Merlin
Buddy
No typical top 5…
wilbur: ideal against titan. Gives your healer more time to load
Jackal: glass ok, but great in events
Wu: glass, but can make a great difference in titians if you can keep him alive
Merlin: No timestop needed
Buddy: great christmas star, have not tried him yet. Some other heroes will proceed him.
Boril 
You love Boril my friend not Boral, cause this cousin still not in game yet 
Rigard
(never go to a battle with out him)
Wu
Gormek
Grimm
Buddy
Limited roster but I love what I have.
Wu kong
Wilbur
Proteus
Buddy
Jackal/Falcon
1 - Wo Kong
2 - Wilbur
3 - Hensel
4 - Proteus
5 - Rigard
Based on the cards and the forums:
Wu Kong - makes every team feels like The Avengers
Proteus - mini Hel
Boldtusk - great tank and buff
Rigard - only 4* that cleanses
Wilbur - brings survivablilty while debuffing others.
Rainbow team:
Wu Kong
Rigard
Wilbur
Caedmon - fast debuffer that hits hard
Kiril - Dragon Banner tank
Merlin
Hansel
Rigard
Grimm
Boldtusk
Merlin and Hansel make a great tag team used together, in fact Hansel and Grimm make a great tag team too. @VFROOD totally agree about Merlin being a timestop.
I like your list. Those would also be mine. However
Buddy isn’t officially a Pulverizer, he is a def down hero for sure, but the pulverizing special is different than his.
Can you give an example?
Cause I don’t have a clue what the heck that words means at all 
Ramming Pulverizer is the name for the special that Tibs, Grimm and Gorm have. The triplets are the only Pulverizers in the game. The special does a defense down ( Def down or D Down)to a specifc degree. Others have D Down skills, but are not Pulverizers. In Buddy’s case is is part of his “gifts” special.
Thanks for teaching me that dear G.C
Its my first time to understand what the hell is the Pulverizer means.
Wich if there was a whisper option between players on forum, would ask before