Jaws is the most iconic, the most memorable, the most visceral, and probably had the greatest impact as a complement to what was going on in the movie, but it's definitely not my favorite to listen to.
My favorite is The Empire Strikes Back. The theme defines the sense of magic in movies for me. I hear it, and everything that I've loved about movies over the decades floods over me. The sense of possibility and imagination. All the good memories about what movies can be. It's really special.
And damn, it was just so easy to take for granted how incredible the music was in The Phantom Menace because of how badly Lucas bungled so much else in that movie.