I like James Horner's work (Titanic, Braveheart)
Danny Elfman (The Nightmare Before Christmas- including providing the singing voice for Jack Skellington, Beetlejuice, Edward Scissorhands, Sleepy Hollow, Planet of the Apes, Batman, etc.)
Hans Zimmer (The Rock, Crimson Tide, The Lion King, Gladiator, The Prince of Egypt)
John Williams (Indiana Jones, Star Wars, Jaws)
Cliff Martinez (Solaris)
Clint Mansell (Requiem for a Dream, Pi)
I've still got a soft spot for The Transformers the Movie Soundtrack (Vince DiCola and Stan Bush among others), always liked the Crow soundtrack (various artists), the Matrix soundtracks (Rob Dougan among many others), and the two films that Trent Reznor has produced soundtracks for (Natural Born Killers, Lost Highway)
I like the soundtrack to Immortal Beloved but that's just Beethoven. Amadeus, too, but that's mostly Mozart.
Someone else mentioned Final Fantasy VII, and if we're going to throw in video games and anime... Nobuo Uematsu (composer for most of the Final Fantasy series), Yoko Kanno (Cowboy Bebop, Gundam Wing, Escaflowne, Ghost in the Shell: SAC), Yuzo Koshiro (ActRaiser), Koji Kondo (The Legend of Zelda, Super Mario Brothers), Harry Gregson Williams (Metal Gear Solid), Michiru Yamane (Castlevania, Suikoden), and Hiroki Kikuta (Seiken Densetsu) are all good
NCBear threw in Les Miz, as well. I wasn't a big fan of the movie score but I do like the Broadway soundtrack. Probably my favorite musical. In that vein, I also like the 90s Disney soundtracks, Aladdin, The Hunchback of Notre Dame, Beauty and the Beast, etc. Mostly done by Tim Rice, Alan Menken, Stephen Schwartz.. with some assistance by Elton John, Phil Collins, Hans Zimmer and others.