Spotify vs Zune Pass on WP7

I'm really surprised that no one has done a comparison of the two because they cost the same and provide a similar service. I understand that Spotify has a few million more songs, which could be a plus in their category.  I also understand that Spotify's audio files are 160kpbs ogg Vorbis, vs Zune's 192kbps WMA.  This means that Spotify will probably stream faster over 3g (with less skips or stalls) due to the smaller file size. However, I have been told that the audio quality is fairly equal, even though the bitrate is lower, due to the different file formats.

 

Anyone use both and have any impressions?