Everyone's on Spotify, so why might you even consider YouTube Music?
As someone who's never used Spotify I guess I don't know what I'm missing out on but I found it interesting all the same to compare them. It's just more economical to have YouTube premium with YouTube music added in for free!
I used GPM until the day Google shut it down. YTM was trash when it came out and still trash when they shut down GPM, not sure if that is still the case. I never canceled my YTM subscription because I use the YTP it comes with. I made the switch to spotify for my music streaming and have no regrets other than the fact they shut down GPM.
Ahhh the demise of Google play music is like a wound that never heals lol. It is a vastly inferior product but still good enough for me.
I'm wishing they would keep doing more with it but the experience has massively stagnated except for the addition of podcasts