2Pac will always be the better Pound 4 pound artist. This rap shit was his calling, not that it wasn't Biggies as well, but to me, I look at Biggie as a dude who could battle his ass off, and made it out of that to record some entertaining songs every now and then. 2Pac had a message that Hip Hop wouldn't be the same without.
Art should teach and entertain, but I'll always favor the guy who is teaching. Same goes for Jay-z and Nas. Nas provokes thought.