1 on 1, directly across from each other, with equal capabilities in their own respective powers; a werewolf (extremely powerful one, however) would tear a vampire lord to pieces. There really isn't that much that could stop such a force, not even a Vampire Lord.
But considering Vampires are known for their stealth, I don't think one would allow that perfect scenario to happen and once someone turns into a werewolf, they are just a blood-thirsty, drooling, loud, hatefully oblivious monster of a thing. I'm sure that would be easy to lure into a trap. Remember, Werewolves can't stay in that form forever so they only got one shot, a Vampire isn't going to give them another one.
I'm not gonna bother going into what-if happenings; "what if he lured him off a cliff/what if he had the ring of blah blah/what if he pressed x, b, and then y and enabled god mode." That's just silly.
When it comes down to it, its all circumstantial. Personally I like being a werewolf because tearing people limb from limb is fun and I like the lore as well as the absence of negative effects.