Which is better for me: Spotify or Rdio?

I've recently decided to subscribe to a music streaming service (to all my friends and family's dismay) and I'm trying to consider which service is best for me. I know there are other streaming providers (and if they are that great, then by all means, let me know!) but I'd like to focus on two providers: Spotify and Rdio. I have no Facebook account (so don't choose that as a plus for either provider's integration), I do have Twitter, and I currently use the free ad-riddled desktop version of Spotify, which I like very much. Rdio seems very appealing, but I want to make sure that their selection is either on par or close to that of Spotify's. On the go, I listen to music on my 16GB Nexus 4 running Android 4.2 with half of the music in local storage and the other half in the cloud through Google Music. So with all that being said, which one do you think is best for me?

Thanks in advance!