Hmmmm, well, going by the rules established by the OP, it's a tough choice (and that includes the staying human option too). But, as my name and avatar quite clearly point out, I'm a fan of wolves, so I'd have to go with being a werewolf.
I don't want to be restricted to only being outside at night either, or having to feed. Especially considering how bad blood tastes (I had a really bad nosebleed once as a kid and swallowed a good glob of the stuff. Never forgot how bad it tasted.)
That, plus Vampires have always come off as the super sophisticated, aristocratic species, where the werewolves have always been the more primal, in tune with nature, "lower class" types. I think I'd just fit in more with the werewolves.