Nier Automata had some masterful usage of music, which can't completely be captured in the individual tracks that you might listen to (though the soundtrack album, which I purchased as soon as it became available, does a very nice job of creating a cohesive musical experience).
The compositions and recordings themselves are very nice in and of themselves, but the game itself has multiple variations recorded of each theme, along with a vocal layer (and for some songs, multiple vocal layers). Depending on what's happening in-game at the moment, it'll crossfade between different the different variations, and if the mood at that point in the story calls for it, it'll add the vocals on top of it as well.
Though I wouldn't rank it at the top of my personal list for favourite game soundtrack in terms of the music writing, I'd have to give it top rank for execution and how it's actually integrated into the game itself.