The only issue with Spotify is that they are missing quite a few major artists. e.g. Garth Brooks isn’t available on Spotify. One of the best sellers of all time - not on there. Kinda annoying.
Edit: actually looks like he sold it to Amazon a few years ago and it was absorbed into Amazon Music where his catalog is now available. Regardless, Garth owns the rights to all of his music except for his 2014 album "Man Against Machine", so the lack of availability is again entirely his own decision.
It's annoying. I can't keep track of all the artists I like and listen to. There's hundreds/thousands.
So if we're going to be pedantic, you can add local files to Spotify on the desktop app and they will sync to your phone, so technically you still can listen whatever you want on Spotify.