I prefer the rdio interface but the social playlists are better on Spotify, primarily due to the efforts of ulyssestone and his Spotify Classical Playlists. His latest includes music arranged and composed by Nico Muhly.
I admit to having a hard time focusing this morning. I started out with the John Cage 25th Retrospective concert album on rdio, then I listened to Messiaen on Q2, and then George Walker on counterstreamradio. Now it's Jonsi from the Muhly playlist.