I don't know that I'd use the word favorite, but the John Williams Superman theme is probably the one most heavily stuck in my head over the 30 or so years since I've seen it.
I could be driving my car or mowing the lawn, and that theme will pop in on my mental stereo.
It even sounds the same as the Star Wars theme (same composer, same influences, same orchestra I'd bet).
As for actual favorite, I really liked the music from the Last of the Mohicans. So much so I bought the soundtrack. On tape. I never replaced it. So sadly, I've been a good decade out from listening to it last. it was the only soundtrack I'd sought out to purchase.