I've been testing Apple Music and Spotify across my apple environment (iphone 6, ipad, mac). It seems there are too many little niggling problems with Spotify, whereas Apple Music "just works". Apple has a much more attractive family plan, so I will give my money to Apple.
I have tried everything to get my music to sync but nothing works. I have enough space. I deleted some music just in case. I had logged off and on numerous times and I am connected to wifi. Nothing I do seems to allow me to sync the music. I do not use playlists because I find them to be a waste of time to set up. I use my phone to select music and then download it to my phone for offline play. It is important I get this to work as I use T-mobile and the service is iffy on my commute to work and especailly when I go for long drives.