John Williams - Empire Strikes Back
All of the original trilogy scores are great, but this wins over the others for the Ice Battle music and Han and Leia's love motif.
David Newman - The Brave Little Toaster
This is a recent re-discovery for me. Surprisingly dissonant and adventurous for a children's film, and probably the reason why many people say this movie "creeps them out". I have fond memories associated with this movie, and I suspect the score had something to do with later developments in my musical tastes. The songs by Van Dyke Parks are also really fun.
Jerry Goldsmith - Chinatown
Very potent mix of the "classic" Hollywood score sound and East Asian music (I am avoiding using the word "Oriental"). Sounds kitschy, but it's lovely.