I use the Fold 4 and I love it. I don't think I could ever go back to using a nonfoldable. I never notice the crease during use unless I run my finger across it. In terms of durability, it's been great. I dropped my phone many times onto concrete and no issues at all. The only problem I have is with the screen protector for the folding screen. Mine is already peeling after around a year of use and it's a pain to get it replaced. You can't really do it yourself and you need to make an appointment at a repair shop to do it. At least it's free.
I use Youtube music and I think it is inferior to Spotify. Offline music is much more seamless, music quality is superior, shuffling a playlist is easier, recommended music is better, dedicated desktop app, and more. The only reason I use YouTube music is because there is more selection.
I'm not sure about Apple music though since I never had an iPhone.
It's another android app for lemmy that's pretty barebones right now. I think the UI looks the best than the other options so far.