[iMore.com]

On-demand music streaming services are made for the hardcore music lovers and audiophiles. Not only should they get to know our tastes and preferences over time, on-demand services are also tasked with letting us have more control over what we listen to, when we listen to it. Streaming radio may be fine for some but if you want to listen to an entire album all the way through or be able to play music offline, you want on-demand streaming.
Spotify, Rdio, Beats Music, Google Play All Access, and Slacker are the best on-demand services currently available with full iPhone support. Now the question becomes, which one is the best if any? And more importantly, which one is right for you?

Full story from the iMore Blog...