Here are Top 10 App Index for Music in September 2014 (by App Annie)

iOS $ Google Play combined, US

Top 10 by revenue

1 Pandora Radio

2 Spotify

3 Beats Music

4 Rdio

5 Rhapsody

6 Slacker Radio

7 Musify by Alfadevs

8 Music Downloader for SoundCloud by Egor Lin

9 FIT Radio Workout Music

10 Songza

Top 10 by downloads

1 Pandora Radio

2 Spotify

3 Musify by Alfadevs

4 iHeartRadio

5 SoundCloud

6 Music Downloader by James Carlay

7 Beats Music

8 TuneIn Radio

9 iTube for SoundCloud by Benyamin Brest

10 Amazon Music