Laptop Magazine tests seem to show Android smartphones on T-Mobile seem to have better battery life than the same phones on Verizon and AT&T.
http://www.talkandroid.com/215445-t-mobile-keeps-going-and-going-in-battery-tests/
New results are in examining battery life for some leading smartphones across carriers and T-Mobile continues to demonstrate superiority compared to Verizon, Sprint and AT&T. Some of the results are quite impressive for T-Mobile and overall paint a widely divergent picture when it comes to battery life. For instance, the Samsung Galaxy S 5 was able to go 10 hours 57 minutes on the T-Mobile network while lasting only 7 hours 30 minutes on Verizon. Similarly, the HTC One (M8) was able to go 10 hours 50 minutes on T-Mobile, but only 8 hours 42 minutes on AT&T.
http://www.talkandroid.com/215445-t-mobile-keeps-going-and-going-in-battery-tests/