Rap and Hip-Hop--most clever lyricists?

I know very little about rap, but I did enjoy 90% of the stuff put out by Public Enemy, both lyrically and musically, and I also used to love The Disposable Heroes of Hiphoprisy ages ago.

Full lyrics here.

Now that I think about, both groups remind me of Gil-Scott Heron who was a great lyriccal rap-preceder.