Goodfellas might have the best soundtrack ever.
I'd put it up there with Good Morning Vietnam and Forrest Gump for best soundtracks.
Best Soundtracks is a great topic.
Excluding movies about music* not sure I'm on board with you on GMV and Forrest Gump partiuclarly the latter that strikes me as a kind of Big Chill too cute soundtrack and retroactively its hard to like Forrest Gump since it won best picture OVER Shawshank and Pulp Fiction. Uhh...whoops.
I'd go with a top 3 of The Graduate, Pulp Fiction and indi pick Garden State.
This also excludes movies like Jaws, Star Wars or Close Encounters or The Sting that had 'scores' specifically written for the movies as opposed to compiling songs from various artists.
Props though as Layla might be the best pairing of a pre-existing song with the overall theme of a movie. The ebbs and flows of that song just perfectly captured the highs and lows for Henry Hill.
* So this excludes not only musicals (ex. Grease), band movies (A Hard Days Night, Purple Rain, 8 Mile) but also movies such as favorites of mine Almost Famous, Singles and High Fidelity that were really about music. Also throw Saturday Night Fever & Footloose into this bag even though neither was necessarily solely about music just cuz their songs are now more cheesy than classics.