Ras Kass is way to up himself. But yeah

Ras Kass

Roots Manuva

Chali2na

Wait, underated in what way? To the mainstream? Or hip-hop in general?

If mainstream. Then also

Sage Francis

Aesop Rock (both will never make it in the mainstream...they're too complex, lyrics too intelligent and music no where near 'pop')..


List goes on and on though, doesn't it? These are just the ones that came to mind at the moment.