I choose the HD7 because I decided to ride the WP7 train from scratch, after long thought ( I still cheat and use my HD2 via WiFi..I'm telling you, it's the best winmo phone..ever

*), if you're into tweaking and hacking, go Android. If you like it simple, iPhone or WP7 or BB is for you..but try it 1st!
*The Dr. is just stating an opinion