He might not be the greatest, but he’s the most accessible and prolific: Daniel Dennett.
Steven Pinker is more a scientist, or he’d get my nod
The top living genius is neccessarily a philosopher, in my books.
Hence I will say Stephen Metcalf, again. He’s certainly the best out of those who have published (that I know of).
Dick Cheney.
Dennett.
Eric Cantona.
Umberto Eco
-Imp
Torn between Tu Weiming and Rodger Ames.
Tu Weiming continues with the tradition while re-inventing it; whereas Ames takes the older stuff and sees it in a new (but shockingly valid) way.
John Searle
Ravi Zachariah 
Searle. I like Dawkins and Dennett too.
Zizek
I think Milan Kundera would be one of the brightest. Of course, he’s not a philosopher per se, but if you read his oeuvre you’ll find loads of interesting theories and thoughts. After all, that’s some sort of “love for wisdom”, which is philosophy itself.
While we’re on that road, I still think the best philosopher ever (for me, of course) is my eight year-old daughter 
bad thing I can’t post Baudrillard anymore.
I’ll second that. Baudrillard would be my #1 choice if he were living.
We are losing our philosophers one by one, Said, Sontag, Derrida and now Baudrillard. Among the living I prefer Eco and Habermas.
Leonard Peikoff
peikoff.com
Kwame Appiah.
At this point, I am my own favorite living philosopher, Christ being excepted.