Mainly Amazon due to its catalog and price, though software isn't perfect and some of their tracks are off (e.g., OG Taylor Swift albums have a lot of tracks replaced with her newer ones).

I'd say Qobuz was the best in terms of sound quality, but catalog was lacking some foreign music I listen to.

Tidal had a decent catalog, but I was a little turned off by all of the different "versions" of albums they had. Supposedly different masters, some versions sometimes sounded better than others, sometimes I couldn't tell. Interesting though, if nothing else.

Spotify and Youtube are probably the most accessible with the best catalog and a good recommendation engine.

Never tried Apple music, but I am very curious about the classical music version they recently announced/released.

Oh, and buy/download what I can if it's not on one of these services, I guess.