I only left Spotify for Youtube Red/Google Music. It was not an easy decision because they have the best music selection and discover imo. They should acquire pandora and then I think they could dominate this space.
Its interesting that you praise Spotify's selection. I love Spotify, have been a Premium subscriber for 4 years, but there are hundreds of songs that I'd like to listen to but have never been available on Spotify. Meanwhile, they're available on Apple Music. Also, some of the songs that I've saved over the past few years have been removed from Spotify's library - just yesterday I noticed that The Safety Dance is grey…
I once complained to Sufjan Stevens' label about his albums missing in Spotify. They basically told me the deal with their distributor in Europe expired and they didn't look for a new one yet. "woops". It took them many months to get the tracks back.