The "greatest philosopher" vote, part 2

As I mentioned a few days ago, the BBC is running a poll to find out who we think the greatest philosopher is. The first phase is over, and we can now choose from the final list of 20 nominees. It’s a fairly predictable list (it would be interesting to find out which of the members was “most unexpected”):
Aquinas, Aristotle, Descartes, Epicurus, Heidegger, Hobbes, Hume, Kant, Kierkegaard, Marx, Mill, Nietzsche, Plato, Popper, Russell, Sartre, Schopenhauer, Socrates, Spinoza, and Wittgenstein.
And my vote? Well, I’m not quite ready to make up my mind….