I've stuck with Spotify since it launched in the U.S. and actually found it to be the best. One area where I think Spotify excels is its desktop app, especially on OS X.
There's a lot to like about Rdio, but last time I used the desktop app it was reliant on Flash, and it would eat CPU so much my fans were always running; has this changed?
I've tried Google Play All Access a few times, and am actually doing another trial right now. But the web player is unreliable, glitchy, and just not a great experience. Using the 3rd party app that wraps the web app makes for an even worse experience, and it appears to require installing Flash even though I configured HTML5 in Labs.
Looks like Beats also has a web player but no native app. How is the experience with this? Also, I wonder if Beats is going to become an Apple device exclusive in the near future -- this would make it less appealing in some respects, though wouldn't completely exclude it for me (after all, I still use iTunes with Mac, iPhone, Airplay). If the Beats iOS app ends up with tighter iOS integration than 3rd parties can achieve, that might be appealing, even though it would unfairly compete that way. Also, I wouldn't mind if Beats was integrated into iTunes and incorporated iTunes-like features (smart playlists, 5 star ratings, etc) -- I'm one of the few people who actually loves iTunes for music playback and appreciates it's strong feature set.
I also find Spotify has a good community in its shared playlists, though I haven't compared with other streaming services.
I love Spotify's preview feature in the desktop app, happy to see it in the iOS app.