If you're looking for the oldschool type go with Biggie Smalls, 2Pac, and Nas.
If you want more modern there's a few different types.
Dark: any OFWGKTA. So Earl Sweatshirt, Tyler, The Creator, Mellowhype, (possibly) Schoolboy Q
Soon2BeMainstream: Childish Gambino, Logic, Cam Meekins, Calvin Coolidge
Different: Kendrick Lamar, Tech N9ne, Hopsin, SwizZz, B.o.B
Moral: Mali Music
Mainstream: Drake, Lil Wayne, French Montana, Chris Brown (anything produced by DJ Khaled).
I could come up with more, just ask if you're actually interested.
Rap is a true art, most people don't agree but it truly is.