I don't actually know yet if I'm even going to vote let alone who I would vote for. I was playing with the idea of changing my party affiliation to Republican so I could vote in the primaries, but I honestly don't like any candidate. In the past I've tended to vote for Greens and Socialists, now I'm reconsidering even that.
The main problem is where I live. Massachusetts is going to Obama regardless. Hell, look at this:

If I vote for Obama, I've wasted my vote on someone who I don't support.
If I vote for the GOP candidate, I wasted my vote on someone who I don't support who won't win my state anyway
If I vote for a Green or a Socialist, I wasted my vote on someone who I do support who won't win my, or any other, state
If I don't vote at all I wasted my vote on no one, but it makes no difference anyway.
I'll probably end up going write in candidate for fun. Or I won't vote at all for president and vote for other things on the ballot.