Hip-hop artists I've liked: Beastie Boys, Dälek, OutKast, The Roots, Common
Hip-hop artists I've heard about but haven't really checked out: De La Soul, Tribe Called Quest, The Fugees, Dr. Octagon
Some of these might be up your alley. They're generally pretty creative and the braggadocio is toned down or ironic. I have mp3s if you want 'em.

Sample Beastie Boys lyrics:

If you try to knock me you'll get mocked
I'll stir fry you in my wok
Your knees'll start shaking and your fingers pop
Like a pinch on the neck of Mr. Spock