Lesser of 2 (or 4) Evils

Yesterday was the Virginia/Maryland/D.C. primary. In spite of the lovely ice storm, I made it to the voting location before the polls closed, still not sure how I was going to vote. I've never voted Democratic in my entire life, but this time I was tempted (open primary and all). Since Romney is now out of the race, who is there left to vote for? I'm not crazy about any of the candidates right now. Huckabee is plain crazy, McCain is a loose cannon (and bordering on too liberal), Obama is likeable, but inexperienced (and a Democrat) and Hillary is, well, terrifying. So, do I still vote Romney (which means nothing now, so why even bother) or do I vote Obama to help keep the Clintons far away from the White House?