I've been trying out a different music service every few months, here's something interesting I found.
Number of songs:
- Xbox Music 30 million.
- Apple iTunes 26 million.
- Amazon MP3 25 million.
- Spotify 20 million.
- Rdio 20 million.
- Google Music 18 million.
I've most recently been using Google Music since I can upload songs albums which aren't available in their library (e.g. Beatles). However, Xbox Music is pretty neat too. It's actually pre-installed on every Windows 8 computer and you can listen to just about any songs without ads in high quality for free. (Not sure why Microsoft doesn't advertise this more.)
Other thoughts: Apple is the only one without a cross platform mobile offering. For I instance, I'd like iTunes radio on Android or Windows Phone. Spotify has by far the best social experience and Rdio has the best designed web/mobile interface.