If you're really interested in choosing the best candidate, first watch this movie: http://www.filmsforaction.org/watch/lifting_the_veil_obama_and_the_failure_of_capitalist_democracy_2011/
If you did, now you know that Obama is the worst possible candidate for the job. Given that Romney is just as bad, I would vote on neither.
Sorry dude, but if those are your only two options, then you're pretty fucked.