For top to bottom quality, my vote would probably be Forrest Gump.
Tier 2 - Saturday Night Fever, Dirty Dancing, Detroit Rock City, Grease, Dazed and Confused, Animal House, Blues Brothers, maybe Top Gun
South Park - Bigger, Longer, Uncut will also always be one that has a special place in my heart... a lot of awesome packed into that one IMO (if you're into off-color sing alongs, at least) even if none made it onto mainstream charts
There are a LOT of others that have one song they're really known along, with maybe 1-2 secondary songs, and then nothing else noteworthy / quite a bit of filler.
Side topic: Are soundtracks still a thing since the world has gone to all digital downloads for music? I don't know that I've even tried to listen to a soundtrack wholesale since the days of CDs...