I just cancelled Spotify after using it for some time now. When I got my Nexus they offered me 6 months free so I ran them side by side to see which I preferred. GPM integration into android made it a no brainer for me coupled with the fact that you have access to music videos, ability to play YT in the background and my integration of my existing library, not to mention the visual overhaul is very nice.
I just wish they integrated with your existing library with GPM on iOS too, and I cold just use 1 app instead of 2. Not sure why they don't as other music player apps can access your library so why Google have opted to not do so on iOS really annoys me.