Even if the two candidates were equal intellectually & otherwise, I'd still go for Obama simply b/c of his age. A young but mature president (hello, Clinton!) commands a lot more respect & has a lot more energy to draw from than an old geezer like McCain. I wouldn't be surprised if that guy strokes out in the Oval Office.
If Obama rocks, and he might, then you'll be assured of getting a strong 8 years out of him. A strong, longterm adminstration will do a lot more for your country and its needed. Do you really want to be doing this *again* in 4 years??