Necromancer Wizard, despite it being a pain in the ass to constantly find corpses to reanimate. That's pretty much the only flaw, and its biggest. Especially in later levels where you need 2 corpses or more per long rest.
Necromancy as a school is very well done I think, Its a pretty solid Curse/Summon school with some hefty damage options if you multiclass into cleric or build for damage. Do you need health? Upcast false life and you'll have some solid bonus HP. One particular enemy is annoying? Curse that mf to skip their turn. You lonely? Summon Gary and Bob to take the agro off n deal some damage themselves.
Only downfall is Necromancy only gets really fun once you get animate dead/create undead, yet the problem with said spells still stands. If the Undead summons were either permanent or just summoned from the ground instead of a corpse it would be more enjoyable instead of a reminder that you're using up a finite, limited resource, and I'd be playing it a lot more.
That, and being edgy is fun.
Conjuration has to be a close second. I feel like a pure wizard then.