Depends on whether you're talking about Star Wars, the single movie, or Star Wars, the series of movies. If you consider the three original movies (Star Wars, Empire Strikes Back, Return of the Jedi) as a single film in three installments it scores pretty high on my list. Not #1, but maybe in the top ten.

I hesitate to call any movie "the best" because it usually amounts to comparing apples and oranges, but my short list definitely includes

Lord of the Rings (the 3 movies considered as a whole)
The Godfather (Parts 1 & 2 - They can keep part 3)
One Flew Over the Cuckoo's Nest
Babe
The Usual Suspects
Fargo
Little Big Man
Dead Man Walking
Dr. Strangelove

That's 9. I guess that makes the original Star Wars trilogy #10.

Bruce