Say what you will about Spotify, but their native iOS app is really top-notch. I keep finding little details that make my user experience so much more delightful. For example, I recently learned that you could swipe left and right on the "now playing" bar on the bottom to move between songs. It feels really organic and I wish other players would adopt it. I also just found out that you can swipe right on songs to queue them up for playback, and now I use it all the time. Dunno WTF happened with their desktop client, though.
Oh, and now that I've learned that you can (secretly) search Spotify by genre ('genre:"progressive metal"') and see the top tracks, my life (and music discovery) have been much improved. I also routinely bulk-add the top tracks from artists I'm investigating to get a feel for their music. Don't see a way to do either in Apple Music.