Black Milk, Elzhi, Lupe, Common, and J Dilla. Those are my favorites. I personally hate Kanye. Common, J Dilla, and Lupe are pretty much givens, but Black Milk is one of my favorite producers and Elzhi's flow is sick as hell.
Elzhi:
http://www.youtube.com/watch?v=KKcrIGj387w
Black Milk:
http://www.youtube.com/watch?v=0HY5r_4xrEA