I too have moved from Spotify to Napster, largely due to constant issues with Spotify not working as well as it used to. The sound quality isn't as good on Napster but I personally don't think either is good enough as a main source anyway - I use these services for having a listen before buying a new album. Crucially, I never have any issues with Napster and the availability of different artists and albums is, on the whole, very good.