4 classes for a group of friends

[Toxigen]

basically you got it right

enc + cleric + tank + whatever your 4th wants to play, literally anything will work...you're going to destroy everywhere you go

do you have any sort of 4 man farming goals? is this just for xp? self found, mildly twinked, or uber twinked?

if you're just doing it to level then the answer is rogue...if you've got your sights set on tougher camps in your high 50s / 60 (juggs, king, etc)...then monk