While this has been hip hop's longest debate, Biggie Smalls & Tupac are inherently too different to fully credit as being the best. Each individual had their own qualities that elevated them to a legendary echelon. While Tupac was an influential individual whose music marked an integral era within hip hop, Biggie Smalls lyricism and flow was on a level on its own.
The two were talented men who were cut down before their prime. It is a tragedy, and it is something that hip hop as a genre is still grappling with. The whole concept of "beef" has led to far too many altercations with guns. Two gifted men are dead because of it.