Plasticman: to often he's depicted as just a stretchy guy. If you actually look at his power set he's more then that.
Vixen/ Animalman: Once you get into some of the more bonkers abilities that some of the more obscure creatures on the planet have you realize how powerful these two are. For one thing they are technically immortal.
https://en.m.wikipedia.org/wiki/Turritopsis_dohrnii
And that's just one creature they can draw from.
The Martian Manhunter: he is literally the Swiss Army knife of superheroes.