My actual real life experience took me down I-95 between southeast Pennsylvania and Orlando. While north of Richmond, Virginia and once in central Florida AT&T's 3G was generally faster than Verizon's 3G. In some places, such as downtown Kissimmee, a magnitude faster. However, the 700 or so miles in between was a different story. AT&T was either EDGE or it didn't exist at all while, with a single exception in South Carolina that lasted about 5 minutes, Verizon was the same speed, or nearly the same speed, that it is everywhere. I was easily able to watch the Canada & USA olympic hockey game on a netbook with a built-in Verizon modem using Slingplayer to connect to a box back home. At the same time, the iPhone on AT&T was timing out just trying to connect to my mail server.
So yeah, I wouldn't believe much of anything you read on this site. Remember, an "expert" is someone who travelled more than 50 miles and showed slides.