I think the library is probably the biggest thing for OP. I mean, when I first tried using Spotify and found out they only had a single track from Blink-182, I immediately stopped using it. They have their entire catalog now, but, I'd imagine still not some songs for OP which, if a service doesn't have an artist/song you want to listen to, why use it?
Too bad Spotify bothers him -- even though it may lack some songs and features, I don't see why you can't enjoy Spotify for most use cases.