1. The Master (still the only vamp in history to kill Buffy)
2. Kakistos (the boy gave both Buffy and Faith a run for their money)
3. Dracula (the 'look I can turn into mist and then reform after you stake me' trick sets him a cut above)
4. Ubervamp (strong enough to place high, too stupid to place higher)
5. Angel (there's a reason this guy got his own series you know)
6. Dru (she killed Kendra, she hypnotizes people, she has visions, she's just got a bunch of stuff going for her)
7. Spike (he had to place below Dru, she pretty much controlled him)
8. Mr. Trick (finally a vampire who realizes that a little thing called the UZI exists... to bad he didn't own one, he might still be alive)
9. Darla (.... just 'cause I don't recall her ever actually doing anything)
10. Luke (he was big and tough, but incredibly stupid)
and an honorable mention for...
11.The Annointed One (you gotta respect a rug rat who can boss around a group undead)
This list of course just takes into account the actual vampires of the Buffyverse. If you want to throw in Vamp Willow and Vamp Buffy I'd be willing to knock Luke and Darla off the list and place Vamp Willow above Mr. Trick (she was evil and skanky... you know, in a good way, but she didn't really seem that tough). Vamp Buffy I'd probably place either just above or below Angel.