I would actually argue that Google Play Music was the best music streaming app that I’ve used. It was great being able to upload music from CDs of small local bands and have it right in there with the other streaming music.
Just today I had a hankering to listen to a specific song through my android auto, and instead of just being able to verbally ask the unit for that song, or even being able to search through the atrocity that is the YouTube Music interface on my head unit, I had to pull over, pull out my phone, search for the band, then click the uploads tab (because uploaded music does not show with the regular search results) and then click the song to get it to play.