Lets see here werewolfs only get dieease immunity and form.
vampires get 25% buff from necomage perk 25% to sneak and illusion spells. Frost resistance. Can easy counter downsides. can leave form at any time.
I think vampires win this contest handsdown
Some of the downsides anyway. I stand by what I said about the appearance being a significant drawback to Vampirism. The character customization menu is impressive, in my opinion anyway. However, vampirism and the impact it has on appearance kind of messes with my understanding of the menu. I've made enough characters that I am able to make them quite attractive, but vampirism screws that up and characters that appear attractive normally tend to be hideous once they have turned. I've been working more with the menu to see how I should approach vampiric characters in the future, but its still kind of irritating that it butchers the customization system and requires having to learn a whole new set of rules if you want to make decent looking characters.
Also, I wish Bethesda would get rid of the busted lip. That feature in particular is one of the major complaints I have with the vampire's appearance. It's ugly, it sticks out like a sore thumb, and I think it makes male characters look absolutely ridiculous because the color is so deep. It makes it look like the character is wearing lipstick. None of the other Volkihar vampires have this feature, why does the Dovahkiin?