Chamillionaire, Kanye, Nas, Jay-Z, Common, Talib Kweli, Wu Tang, and basically most northern rappers. The south doesn't really have any good mainstream artist w/ the exception of Chamillionaire and maybe T.I.
Cee-Lo Green. of course, right now hes doing Gnarls Barkley, which some people say isnt rap. He was the reason Goodie Mob was any good, and its obvious now. Outkast are still amazing, when they decide to do something.