For me personally, the absolutely best vampire movie ever is the original Salems Lot (NOT the remake!!!).
To me, it's a magical movie. Have you ever watched a movie that pulled you in so much that you could almost sense everything in it as if you were a part of it yourself? That's the effect Salems Lot has on me. Of course, this is just MY personal opinion - but there is absolutely NOTHING I would change about that movie, it's as close to perfect as it gets.
Also, the movie has what I consider to be one of the scariest scenes of all time. Again, just my opinion...
I'm not sure how to insert youtube videos on this site, but I will try - this should be a link to the scene I was talking about
:
http://www.youtube.com/watch?v=w1unHCE_Npw
A VERY close second would be Nosferatu, that movie is really a work of art. Of course, the two vampires from Nosferatu and Salems Lot are kind of similar looking -and probably the only two vampires that I ever found truly frightening, rather than attractive, which is how I always felt about all the other vampires.