Lycan and Vampire are like Ben C said, strengths, weaknesses. The most annoying part about the lycanthropy is that everyone says you smell bad. For some reason i dont mind as much if ppl say "I don't like those eyes, they got a nasty hunger to them." I wish the ppl of skyrim would respect one's player the more powerful they get, like even if you beat the main quest and have fortune and fame AND be a morally good player they will still tell you that you smell like a dog if you're a lycan/companion. The only ppl that start to show respect are some of the mages at the college and ppl you've already helped. I wouldn't pick because its fun to claw/drain/eat/reanimate and rampage with both!!!