I *love* the nice quick download of the playlist and offline Spotify quality is good enough for me. But, since the Spotify watch app update, although some things are improved (staying logged in, remote function etc), I'm finding that offline, it will get stuck at the end of a track and not go to the next one. This is the last thing you need while running, it puts you off completely.
So what I now do is loop Spotify through my sound card on my PC and export tracks as MP3s. Great quality, probably not strictly legal, but since they can't sort out their own app so I don't have to do this, IMO, morally, it's justified. I pay my subscription, too.
I would love to quit Spotify and change over to Tidal but I have a family subscription and I doubt my kids would ever speak to me again!