A tough call between Star Wars and Casablanca, but Bogey won in the end.
It might have been tougher if I hadn't seen the restored version of Star Wars more recently. I discovered that going back to see it as an adult, many of the B-movie conventions -- Storm Troopers who can't hit a stationary target at 100 yards, the princess emerging from days of brutal interrogation with perfectly coiffed hair and lipstick, etc. -- bothered me more than when I saw it as a teenager. At it's heart, it is what Lucas and Spielberg said they wanted it to be -- an old-fashioned serial with A-level production values. It's a thrill ride, and a brilliantly crafted and influential one, but I have a hard time seeing it as more than that.
Casablanca on the other hand... Well, it's a classic in every sense of the term...