The problem with the vampire folklore is that every has their unique version (some better than others). However, while vampires used to be slightly similar in each version, nowadays an emo with red eyes could be a vampire.
In my opinion, the best/most lore friendly versions of vampire are the ones that emphasize their inhumanity rather than their humanity (especially since werewolf lore does the opposite). In the case of elder scrolls, vampires are cursed to become undead. I think the game should focus more on their monstrous side like they did with dawnguard in skyrim.
Essentially, have the normal vamp perks when untransformed but then have a transform ultimate similar to werewolves (werewolves should also have perks when untransformed btw).