Best ever vampire film? That's hard to say, because I love the genre and I have a hard time choosing just one. I guess it depends on my mood. In any case, while I like
The Lost Boys a lot, I don't think I would ever put it at the top of my list, mostly because I hate the ending; the filmmakers pretty much throw common sense and logic out the window.
Films that vie for the top honor, for me anyway:
Dracula (1931)
I know a lot of people don't care as much for this classic as they do for some other vampire flicks, but I really like it: although it is somewhat stagey, it has atmosphere to spare, Dwight Frye's portrayal of Renfield is positively delicious, and of course Bela Lugosi is the definitive Dracula.
others that rank near the top:
Near Dark
Two words: redneck vampires. Need I say more? I didn't think so.
Fright Night
I love this movie. I know, I know; it screams 1985, but all the characters are great, and it's one of the better examples of mixing horror and humor effectively.
That'll do for now. I'm sure other folks will come up with plenty more.