having one of each at max level I have to say werewolf, it's not that vampires aren't fun and all, it's just that after a while the whole feeding thing becomes a hassle, (unless you're doing a no fast travel run, I've heard it's easier to manage and more fun to do so if you don't fast travel, not really sure though) and while I never use beast form except for the faster running it does have disease resistance, but vampirism, while nice to have, just doesn't feel like that much of a boost (although arguable it isn't meant to, because it's not a perk, it's a disease) and just hampers my ability to focus on other elements of gameplay.