Agree that AZ is underrated. I don't know about most underrated ever.
Agree with the above that Doe or Die is his only great album. However Aziatic was very good. Pieces of a Man, The Format, and AWOL were good albums too.
I'll nominate Grand Puba as the most underrated ever, because I think I'm the only person who has ever mentioned him in these threads.
Part of him being underrated is his own fault though as he didn't have enough output or as long of a career as he could have. He was said to be lazy and missed studio sessions often. But he was one of the most gifted rappers out at a time when a lot of great rappers were out. Insane flow.
This is one of the best hip hop singles ever in terms of being commercially appealing(for the time), and still rapping his ass off.