"Salem's Lot" is still the scariest in my book, if for no other reason than it left a deep, scarring impact on me when I first saw it at age six. The makeup effects are as good as any I've seen since, though. They relied on real-life techniques, rather than the dime-a-dozen digital morphing effects in every vampire movie and TV show today.
As far as good 'n' entertaining, I like:
"The Lost Boys"
"Fright Night"
"Interview with a Vampire"
"Bram Stoker's Dracula"
"John Carpenter's Vampires"
...though each has its flaws, of course.
The Hammer films were also enjoyable (like the Cushing/Lee ones Dean mentioned before. I remember seeing one called "Captain Kronos: Vampire Hunter" when I was a kid, and being impressed with it. It was in the $5.50 bin at Wal-Mart a while back, so I picked it up. It wasn't quite as good as I remembered (they never are), but what was funny was that the "Captain Kronos" part was in tiny writing on the front cover, probably so people would think it was a "Vampire Hunter D" movie if they didn't look very closely.