Rdio>Spotify. The iOS app is heads above the Spotify iOS app. It's got a web browser based service, and it's slicker visually. I love Rdio.
I would agree with you except that Spotify, imo, has better music access. For instance Sherwood is unavailable in the U.S. on Rdio, but they're available on Spotify.
Rdio wins for having no audio ads though