Wow...It's actually pretty hard to get powerful as just a normal human.
But if you don't turn into a vampire then you will be a much more powerful necromancer. Necromancers also do not need to eat, drink, or sleep, but as a necromancer you also do not need to feed on blood, unlike a vampire. So if you can manage to become super powerful and take the necromancer by surprise (possibly by using your sneak skill), then you will be the ultra champion.
EDIT: It may also help to become a dwarf because they have a chance to enter a martial trance, which boosts combat abilities, during intense battles. Or you could become an elf because they have higher agility, which might help you dodge those arrows that might paralyze you from the waist down.
EDIT EDIT: I just got a group of 9 necromancers to join me. Unfortunately, their leader won't give me a legendary quest until I prove myself more.