So how do I sort this? I've used apps to join my playlists but I'm not listening to Spotify when everything sounds like it's under water but YT music keeps playing the same songs over and over. The only thing I've found is to go to YouTube, listen there for the algorithm and the update YT music for the sound quality but there must be an easier way....surely....

I use YouTube Music as it comes free with YouTube Premium. I've created a bunch of playlists and mainly use those when listening to music. Or just select specific albums. 

Doesn't Spotify have the lossless streaming option these days? If it sounds like ass, it's probably your equipment.

EDIT - reading around, and some people are suspect of the quality of Spotify lossless, so maybe I'll take my comment back. Who knows?

It's complete bollachs compared to YT music. It's like listening to a YouTube video by an amateur. 

Call me old-fashioned, but I have actual files on my external HDD. I use online services only for finding new music to listen to, and let me tell you, that's a lot of effort for very low yields, so I don't do that very much. I've been using mostly YouTube for that, although I dabbled in Spotify a bit in the last year until it threatened me with a potentially worse time, seemingly because I had run out of free something. I've also discovered YouTube Music to be quite nice, because whereas YouTube often delays playback start when using an adblocker in Firefox, YouTube Music has no such nonsense.

If YouTube Music has the same audio quality as YouTube itself - and I have no reason to doubt it - that's some really low-quality audio, I can tell you that much. Not by my ears though, because I'm not exactly an audiophile, but judging by what quality options a YouTube downloader app offers, it's pretty bad.

Same for me. While there are plenty of issues with YT music and how it integrates with YT proper, I do find it to be the better music provider. The fact that the overall package is dirt cheap where I live, is a bonus. It's actually the only subscription I have outside of my telco provider. 

YT Music has way better audio quality than YouTube. 

Other: physical albums through a stereo for me.

All algorithms are ass.

Apple Music quality is simply the best. If you're a music fan, just go and get it. You won't regret unless you nitpick some minor stuff.