I don't listen to even 8 million songs. The problem is raw numbers don't really tell the story. Netflix has a huge catalog by raw numbers... But it's fairly well-agreed that they've dramatically reduced their offerings of non-Netflix-produced popular titles.Apple music has 90 million songs. Spotify is the next largest at 82 million. So I wouldn't say selection is not great. I like that Spotify allows me unlimited downloads to store on my devices for use away from cell coverage.
Sound quality is good with Spotify but could be better. They don't have lossless Hi-Fi yet, but it is coming this year according to their press.
In other words, the total number is meaningless. I don't care if you have 82 million other songs if you don't have the one I want to listen to.