Without even going into the merits of Spotify's playlists as you mentioned, one reason I would personally prefer Spotify over Apple Music even if we assume rest

Without even going into the merits of Spotify's playlists as you mentioned, one reason I would personally prefer Spotify over Apple Music even if we assume rest of the things equal would be to support a small player(compared to Apple). Apple, a company already well entrenched in so many fields controlling one more is something I would not prefer to see. They already are at a huge advantage in even controlling this market as owning iOS and iTunes makes it very easy for them to push their service.