I disagree that Mog is ahead of the competition.

For me, while Mog has more songs, they lose to Rdio in their UI, their iPhone app, and the social aspect of the service.

When I was comparing them, it was neck and neck between the two, but I couldn't stand Mog's crashy AIR player compared to Rdio's rock-solid AIR player. The Rdio website is much more intuitive and usable, IMO. Also, the new Rdio for Mac app is crazy awesome. The Mog iPhone app used to sign me out all the time, too, which was really irritating.

I've also found a lot more new music through Rdio than I ever did when I was using Mog. The social features are nice because I've been able to find people who like the same type of music and then listen to new music they discover.

It's all a lot of little things, but they added up to make Mog really quite unacceptable for me.

MOG was around way before Rdio. And for me, its all about the music. I could care less about social features and never ran into problems with the AIR client or the phone client.

Also, MOG just finished a HTML5 redesign anyway.