Samsung Focus Flash or HTC Radar 4G 0r Nokia Lumia 710

I'm interested in getting a WIndows Phone device as my first smartphone, stepping up from an iPod touch. I'm personally leaning towards either the Focus Flash or Lumia 710. From a specs standpoint they are more powerful than the Radar. I like the design for all three phones. I'm also leaning towards the Focus Flash beause it is on AT&T and I am not so sure about the longevity of T-Mobile. I want a phone soon, but wondering whether it is worth wait for the Lumia when it comes out in January.

So, what do you guys think? Which is a better device.