Used to enjoy soundtracks because they allowed you get a bunch of good music from a specific genre or era. American Graffitti, Forrest Gump, Dirty Dancing, The Big Chill, Saturday Night Fever, O Brother Where Art Thou? Tarantino gets a lot of credit for his soundtracks, but Paul Thomas Anderson is right there. Boogie Nights has a really underrated soundtrack.
And then you have the kind that began in the '80s stacked with singles, Flashdance, Fame, Footloose, (See Dean Pitchford) The Bodyguard, Top Gun.
Not sure where Broadway/Musicals soundtracks fit in - Grease, Rent, Wicked, Music Man, Guys and Dolls. The Disney stuff.
Also a fan of the soundtrack to Gettysburg and Hoosiers. Pure Country is George Strait's biggest selling album.
And you have to talk about Adam Schlesinger's work on That Thing You Do! The song is the key to the entire movie and it still works. The album was entirely composed of original material to mimic the era - Tom Hanks even wrote a couple of them.
Schlesinger's other credits include "the song" for Music and Lyrics, and Colbert's Christmas.