I personaly cant think of a clear winner here but here are a few of my contenders
Highlander
The Doors
Almost Famous
Saturday Night Fever
The Lost Boys
Resevoir Dogs
The Virgin Suicides
Lost in Translation
Eternal Sunshine of the Spotless Mind
NOT LOTR.
My faves this time around:
Under Fire by Jerry Goldsmith. How this lost the Oscar is beyond me.
Burn! by Ennio Morricone. Okay, this is a weird score but damn. It’s so bizarre. Love it.
Gui La Testa by Ennio Morricone. I guess I’m in a Morricone mood. Great score. Bizarre.
Omen III: Final Conflict by Jerry Goldsmith. Sucky movie, great score.
Farenheight 411 by Bernard Herrmann. Brilliant. Just brilliant.
The Wind and the Lion by Jerry Goldsmith. Love it. Another “Why didn’t this win an Oscar?” moment. Goldsmith had lots of those.
The Devil’s Own by James Horner. I’m not a huge Horner fan (he’s good, but not someone I collect regularly), but this is a fantastic score.
The Ghost and the Darkness by Jerry Goldsmith. Another outstanding score by personal favorite Goldsmith.
Dracula by John Williams. I love Williams, but so often he gets pigeonholed into doing those sweeping “Star Wars” type scores. This is a little different.
The Missouri Breaks by John Williams. A pre-Star Wars score that is so unlike the John Williams you are accustomed to. Brilliant and just a little bizarre. A must-have for Willaims fans.
The Day the Earth Stood Still by Bernard Herrmann. A masterpiece.
Rambo: First Blood Part III by Jerry Goldsmith. Goldsmith scored a lot of bad movies, and did them exceedingly well. I’ve never seen this Rambo film (so perhaps it’s not crappy after all) but I do know that the score is quite good.
Scent of a Woman by Thomas Newman. Wonderful score.
Jaws II by John Williams. Speaking of bad movies—believe it or not, this is a great score.
Conspiracy Theory by Carter Burwell. Great jazzy score. Lots of fun.
Frantic by Ennio Morricone. Insanely wonderful.
Marco Polo by Ennio Morricone. Technically a TV miniseries score, but it’s so great I had to mention it.
Time After Time by Miklos Rozsa. It just got under my skin.
I could go on and on and on, but I won’t. At least not until next time. 
Ack! I spelled Fahrenheit wrong. Sorry!
See also the earlier thread: Best Soundtracks
I personally put Elmer Bernstein’s soundtrack for THE TEN COMMANDMENTS among the greatest ever. And Howard Shore didn’t do badly on the LORD OF THE RINGS, neither.
I like Han Zimmer’s work quite a bit. My favourite of his are:
Black Hawk Down- It introduced me to Rachid Taha. There is also a wonderful version of Minstrel Boy by Joe Strummer and the Mescaleros
Tears of the Sun
I also enjoyed these:
Pirates of the Caribbean
Braveheart
Everest- Soundtrack to the Imax movie.
Lord of the Rings-Especially The Bridge of Khazad Dum, Lothlorien, and Helm’s Deep. This also introduced me to Emiliana Torrini, whose music I have enjoyed since.
Shrek is quite the toe tapper.
The Commitments has faithful play in my CD player after all these years.
Chocolat is fantabulous.
Easy Rider
Rollllllllllllllllllllllllllllllllll another one, just like the other one.
The English Patientt especially that Hungarian music which is like nothing I have ever heard before. I sends shivers up my spine.
The Good, The Bad & The Ugly - Morricone
Repo Man - Iggy Pop, Suicidal Tendencies, Circle Jerks etc.
Straight To Hell - The Pogues, Pray For Rain, Joe Strummer
Rock n’ Roll High School - Ramones
Apocalypse Now - Coppola/Mursch
And for some reason effects my ability to spell!
To Live and Die in LA
Mark Knopfler’s soundtrack for Local Hero.
Three of my favorite soundtracks:
“The Shawshank Redemption” - Thomas Newman
“Blade Runner” - Vangelis
“Passion” (Soundtrack for the movie “The Last Temptation of Christ”) Peter Gabriel
Of these three, I favor Peter Gabriel’s soundtrack the most with Thomas Newman’s a close second.
Once Upon A Time In the West (Ennio Morricone)
Pulp Fiction
Kill Bill, Volume 1
Grosse Pointe Blank
Lock, Stock, and Two Smoking Barrels
The Virgin Suicides (and I wasn’t even a huge fan of the movie!)
Me too, Dex. But I traded it for a copy of The Vikings at a time when both were hard to find.
Other favorites off the top of my head:
Havana
Spellbound
Heat and Dust
The Shadow of Your Smile
Dances with Wolves
Out of Africa
The Shadow of Your Smile
The Pink Panther
Hedwig and the Angry Inch
The Exorcist.
I’m no expert, like some of you guys posting herein. I have no idea wheter the LOTR soundtracks will hold up as some of the best ever, but they are my favorites.
Other great ones have already been mentioned -
Good Bad and Ugly
Magnificent Seven
Exorcist
also
The Great Escape
To Kill a Mockingbird
So very glad you mentioned that one twickster. I second The Commitments Vol 1 & 2 . As for a guilty pleasure, well there is always Dirty Dancing .