It would be helpful if people posted location and carrier...about half the posts miss one or the other.
It appeared AT&T was faster.
I agree that more location data would be helpful. All my tests were done in suburbs outside of Detroit. AT&T may in fact be faster but I just showed a 42 down speed test on Verizon so their top speeds can be great too.
My main point is that most people on Verizon will be in LTE areas far more often than people on AT&T and sprint.
I'm not saying this difference exists between Verizon and AT&T, but how much real world difference is there really on an iPhone getting 40Mb and one getting 35Mb? From what I've seen the speeds are pretty great for the most part from all carriers. I don't think you will notice much difference in HD streaming or web browsing between LTE on different carriers.
I think the biggest difference between the carriers' LTE is that Verizon's LTE coverage area dwarfs the others so most customers will spend more time on LTE and less on 3G with Verizon.