My first pick would be simultaneous voice and data, then the WiFi hotspot - this will be good for being online all the time if I need to use my laptop for any work while I'm on the go anywhere, screen size comes in the 3rd place it would be great device for games and watching TV, Movies, reading e-books on the go, and finally WiMax 4G, as it is still limited in availability.
Oh, another thing would be, as the Google TV is coming in the near future, this will be a very good device to deal w/GTV, and above all of that it will be a gift from my best Android forum on earth