I mean, DOOM, but close seconds would be Andre 3000 (or Big Boi, honestly), followed by Gift of Gab. Edit: I also have a big soft spot for Serengeti, particularly the album "Family and Friends".
I'll check out the other guys you mentioned, but Outkast is fantastic
Happened to revisit this thread, I nabbed Aquemini on vinyl and I can only describe it as the most juicy sound to ever come out of my record player.
No problem! I will say this: Serengeti is a bit of an oddball - the way I usually describe him is anti-rap, kinda like Jeffrey Lewis or Daniel Johnston are anti-folk. Hyper personal, kinda mundane slice of life lyrics, never takes himself too seriously. Kinda like Open Mike Eagle, if you listen to him.
Sounds like I'll enjoy him cause I love all of Hellfyre Gang!