Another factor can be that Verizon and Sprint are 3G speed and AT&T is effectively 4G in those markets where AT&T offers 4G connection. http://www.phonesreview.co.uk/2011/10/23/att-iphone-4s-is-4g-capable-more-like-3-5g/
Battery life complaints with other (Android) 4G phones is a common issue.
“Battery life complaints with other (Android) 4G phones is a common issue”
I have a new Bionic (Droid) phone.
When I’m in 3G territory, my battery life is twice what it is in 4G. That is all without using either 3G or 4G, existing off of WiFi.
Worse yet, when I leave home, the unit is horrible at switching automatically to 3G or 4G — often I need to cold boot it to get it to hook up.
Motorola, via Verizon, promises a fix “with the next software update.”