One philosopher to rule them all

Who was (is) the greatest philosopher of all time? (I know, the question is completely useless and quite possibly meaningless. Still, I think it's a bit entertaining.) Depending on who we classify as a philosopher, it's either impossibly hard or ridiculously easy. Was Bertrand Russell a philosopher or a mathematician (or logician, or whatever)? How about Gottlob Frege? Charles Sanders Peirce? Alfred Tarski? Ludwig Wittgenstein? If they were all philosophers, I can't decide. If none of them were, the answer is David Hume, hands down, not even a contest.