It is simply Spotify. The app keeps getting better with each passing day, and it is clear to see the efforts the team put into building a very good app for music lovers. I've been using Spotify for a long time and haven't thought of making a change any time soon.
Spotify is quite popular. I would guess it is because of how consistent they've been with making cool updates most music players like. That is not to say that Yt music is never good, but Spotify is the one that I've always liked and still pay monthly subscription for.
That's right. I've got no regrets for sticking with their brand for a while.