vampires hands down, though it depends on the age of the vampire. A new blood (just been converted to darkness) would probably be an even battle. New bloods will burn once the sun comes out too, so thats a disadvantage they have.

But if you take a more powerful vampire such as Vlad Drakula (as an extreme example), there's no way a werewolf could win in theory, since the only way to kill drakula is cut off his head and put a stake through his heart. Werewolves according to legend have no control of their abilities in their transformed state, so they wouldnt be able to perform that specific action.