Rainbird on 30 October 2011
I'd definitely pick WP7 over Android and iOS.
The key difference is the way things are organized. Android and iOS gives you apps for doing all your stuff, where WP7 tries to keep things integrated into logical hubs. All music you listen to can be controlled from the Music+Video Hub, regardless of where you're playing it from (same goes for videos), and People Hub contains all the information you need on your contacts in one place, rather than your phone contacts being in one place, your email contacts in another, facebook contacts ..., etc.
I'd take a WP7 phone for the interface alone. 
