if you want groups constantly, Cleric/ENC
if you want soloability/farming, ENC/SHM, and to a lesser degree NEC/MAG/WIZ
if you want hard mode pick any melee untwinked.
if you want super hard mode pick a High Elf/Erudite/Dark Elf hybrids.

To answer your question, enchanter.

I think bards would be a pretty close second if players did a better job of utilizing their toolkit.

and not just afk mana songing

I just want to say I look forward to this thread hitting 200 pages.

DE SK isn't hard :)
Well apart from faction, but more of a bother. I'd name wood elf ranger as hard mode (or as you say super hard but meh), though not much harder than human and helf ranger, just by a few starting stat points on str/sta. I'd happily roll a DE ranger though :D

I rolled an Erudite Paladin a while back and his life is hilariously hard. Blue con gnoll? Prolly gonna die. Even con? No way

I imagine that's with fungi/blade of mourning and cloak of flames? :p

want unlimited powers?

apply as a GM