Are you totally disregarding story, pace, acting performances, narrative, art style? If the movie in it self sucks with awful an awful story and actors, but a great soundtrack the movie will still suck.
The music needs context if it is going to be great. One example is the movie
Irreversible(2002) where the
soundtrack is nothing I'd listen to freely but in the context of the scenes wherein it is used it is great.
Furthermore, the "modern movies in the last 20 years"-statement is so wrong. Have you not seen the movies by Aronofsky with Mansell's soundtrack? Or Gone Girl, Moon, Fight Club, American Beauty?