Let's base this on some different criteria:
Charisma: About even, edge to Tupac though
Natural Ability: Eminem. Tupac is not even close.
$$$ Grossing Ability: Tupac leads this one, Eminem still has chances to beat him though as he's not dead yet.
Attention-grabbing ability: I'd have to say Eminem here, when you look at all the different types of publicity he gets: good, bad or shock value.
Versatility: No question here, Eminem.
Other: Both owe a lot fo their success to Dre, so I call it even here.
WINNER: Eminem.
