Here's a list for you to run through:
"Underground" ----
P.O.S. from Doomtree Records
Sims from Doomtree Records
Common Market (A.K.A. Victor Shade) - Common Market stuff is better IMO
Blue Scholars
Macklemore + Ryan Lewis
Yonas
Grieves (From Rhymesayers Entertainment)
"Mainstream"
K'naan
Lupe Fiasco
Kid Cudi
B.O.B.
No Sig For Now....