I mainly use Youtube. I'm mostly listening to remixes and pretty obscure small artists I find randomly, so most of the stuff I won't find anywhere else. Otherwise I use Prime Music but only the limited version. If I find something i really like I look for download options like Bandcamp or similar, where smaller artist often sell their tracks für less than a buck or even give them out for free.
There is an extension on browser which you can use it and download any music from YouTube if you want.