Well AT&T and Verizon have an LTE network if what I have read is correct. No experience with AT&T but on Verizon it is fast. When I browse website and youtube I feel like I am on a cable modem. Downloading files as well like roms for my android are quick. Even with 300+MB downloads. My friend has sprint and I have used his android 4g phones and they are not that quick. Quicker then 3G but not as fast as LTE. The 3G is slower then Verizon 3G. He has an iPhone 4s now and the 3G seems a little faster then his previous phone. My GF has tmobile 4G. It feels like 1x when I use her phone. Not sure why but some websites on her phone are super slow but fine on mine. I even tested both websites at the exact same time. It can be reproduced every time. No idea what tmobile's issues are. Hope this helps.