If you're talking Skyrim, vampires and werewolves both have their benefits. Werewolves might seem more durable but because the vampire's drain life spell also heals them of their Health while damaging multiple opponents, I'd go with the vampire. I still have a werewolf build though, and nothing is more satisfying than tackling and eviscerating a bandit chief.
Being a fan of fantasy games and the gothic horror genre since I was a little girl, I've always liked vampires more than werewolves.
In the old tales vampires had the strength of 20 men, could seduce anyone with a glance, and had all kinds of cool powers that differed from culture to culture. They were also immortal, and could only be killed with some kind of special material or ritual.
Werewolves were simply men that could assume wolf form, or "hybrid" form, where they were a cross between a man and a wolf. I assume they would be stronger than an average man but not much. They would also have the ability to track by scent. It was only recently that we started having super-humanly strong werewolves that seemed to gain 3 times their body weight in mass, out of nowhere, when they changed.
To me, vampires would be much scarier as an opponent. Anything that can actually take control of your mind is horrifying to me.
On top of all that think about this:
All a vampire has to do to deal with any mortal threat, is simply outlive it.