The three soundtrack albums that come to mind are Shaft, Reservoir Dogs, and Saturday Night Fever; I’ve played them all many, many times.
Easy Rider
The Blues Brothers
Forrest Gump (shit movie, however)
Footloose
Titanic
South Park: Bigger, Longer and Uncut (with Team America: World Police as an honorable mention)
I’m shocked no one has mentioned Grosse Point Blank. Like Purple Rain its a soundtrack for a moment in time.
(Purple Rain is up there for me since I was a Senior in High School in Minneapolis when it came out - there is no separating the music from the time and place for me).
The Warriors
The Blues Brothers
The Good The Bad and The Ugly
The first two, you don’t even need to have seen the movie to love the music.
This. And a lots of others that I can’t be bothered to pick two from.
Beat me by an hour, but GPB is 1B to my first choice, Fast Times at Ridgemont High. Trying hard to think of a 3rd…maybe The Blues Brothers