Greatest Philosopher?

BBC Radio 4's In Our Time is still running the Greatest Philosopher Vote (until early July). The current frontrunner - according to the moderator, you don't get to see it online - is, rather questionably, Karl Marx! Since he is probably the one contestant with the best claim to the scrapheap of history, we cannot have him winning, can we. So go and vote your personal favourite (mine's Sir Charles Popper, of course)! There's a lot of interesting material there, too, not least a philosophy quiz, which I pretty much flunked with a reasonable score ...