What rap/hip-hop artists are popular now?

Kanye West, for one.

It is official music video and interesting! See here:
http://www.youtube.com/watch?v=83o-cfoNeTo

You posted two years late

Nobody. There are very popular so-called rap/hip-hop artists today, but there music has nothing to do with real hip-hop. It's a fake thing. Meaning also the ones mentioned by you. All the real rappers say their music is almost dead. Real hip-hop was done by De La Soul, A Tribe Called Quest, Salt 'N' Pepa, Naughty By Nature, Black Sheep, Pete Rock and C.L. Smooth, Wu-Tang Clan, Arrested Development, BDP, EPMD, Digable Planets, Fugees, Domino, etc.