Lots of differing opinions, but I guess I'll actually explain my reasoning.
To clarify, I'm also on all Apple and still prefer Spotify. It's a cleaner interface, beginning to host some of the most-popular podcasts, and its curated playlists are far better than what Apple had to offer. Apple has some exclusivity, but that's by a couple of hours, it's honestly not that serious. There are free trials for both, so I recommend that you just figure out which one caters to your tastes better. As for quality, Apple Music is on AAC which is more or less the same as Spotify's MP3's on high. If you're looking for quality, you could always get Tidal, but eh. Tidal's interface is pretty bad, it lags and the library is lacking. You're better off downloading 320MP3's and putting them on your phone. (
)
I can't justify paying for Youtube because those a$$holes at Google decided to put listening to music/videos on alt tabs behind their paywall. I refuse to pay for something they offered for free until the iPhone 5 came out.
Overall, for new music and the size of the library, Spotify (college account makes it cheaper. Easy to get these) + Soundcloud for anything new is the best combo. You'll probably use Spotify more on your phone, while Soundcloud is better used at home if you're vibing/working/chores. For me, it's the best bet and I haven't felt the need to switch since 2016.