If you enjoy USING your phone AND having it last more than a few hours, DO NOT BUY AN HD7!!! I'm typing this on my HD7. It's plugged in at 10 am my time, as I have been up since 6 and listened to music (onboard, not streamed) for 1? hours and browsed the internet (just Facebook and tech blogs, no videos or anything) for for about 15 minutes and left it untouched for the other 2? hours, and that dropped it from 100% to just over 50%...
The Lumia has a faster processor, can accommodate a BP-4L 1500mah battery without modification or a larger battery cover, and has the best exclusive apps, as well as the clear-black screen(readable in direct sunlight). It also has the best signal strength and call quality of the T-Mo WPs.
The Radar has the only FFC of the bunch, as well as the best main camera of the T-Mo options, and the best battery life of any WP to date on any carrier. Also, while not as impressive as the Nokia suite of apps, the HTC exclusive apps are good. Sound Enhancer is amazing. The SRS setting can make music sound incredible through $2 earbuds-and I'm a former recording studio tech. (read: extremely picky on sound quality) The Photo Enhancer has some cool filters, and the HTC Hub is, IMO, the best weather app on the marketplace. It would be my choice if I wasn't so burnt on HTC because of my HD7.
Please don't buy an HD7.