Actually there's more originality and diversity in Hip-Hop today more than ever, the problem is that the music itself isn't really good. Guys like Schoolboy Q, Earl, Tyler, Danny Brown are new-age rappers but I don't really enjoy their music that much, it's just way too different from what we used to know.
Kendrick and Freddie Gibbs are closer to the 90s stuff, and both of them are easily the best rappers out right now.
But if you want true 90s Hip-Hop in 2013 then you better listen to foreign Hip-Hop, because a lot of them have do use that 90s Wu-Tang East Coast sound in their songs.