Depends what type of Rap,

Gangster rap
hip hop
Underground

etc etc.

Recently started listning to Tony Yayo, i like 'pimpin' :P

My favs are

-Notorious B.I.G (new album aswell)
-Big L (Fav Old school Rapper)
-G unit + 50Cent (Dont ask, i hate them but like the music)
-Nas
-Fabulous

Stuff like that