As a former Google Play Music user and lover, it was the recommendations. I haven't found another service that shows me even a significant fraction of the music I like that Google did. I've switched to Spotify but it constantly recommends songs I've already heard or don't like and the shuffle feature gives me the same ~50 songs from a large playlist. It's something I've accepted but I miss the Google recommendations deeply.
As a former Google Play Music user and lover, it was the recommendations. I haven't found another service that shows me even a significant fraction of the music I like that Google did. I've switched to Spotify but it constantly recommends songs I've already heard or don't like and the shuffle feature gives me the same ~50 songs from a large playlist. It's something I've accepted but I miss the Google recommendations deeply.