I've never read any of the Twilight books or seen the movie, so I can't really guess at just what differences the vampires in the two separate universes might have, but from what I have seen of Spike, of the way that the character is both written and acted, my money would have to be on him, no question. Spike is a fighter, but more than that, he is a warrior. He thrives on the fist and fang conflict. The stronger his opponent is, the harder he fights. He's like a pit bulldog, small, compact, amazingly powerful, oblivious to pain, and totally focused on the fight. Knock him down five times, he gets up six times. He's the Slayer of Slayers. Forget about bad to the bone, Spike is bad clear down into the marrow. Edward better get his affairs in order if he plans on tangling with Spike, cause that's a party he ain't comin' home from.