PCWorld recently tested the 3G networks of AT&T, Verizon, and Sprint
in 13 different cities across the US. They've now posted the results, which show that Sprint and Verizon are neck-and-neck for reliability, while AT&T has consistently higher upload rates. From the article: "Across more than 20 testing locations in each of the 13 cities we tested, Verizon had an average download speed of 951 kbps. Verizon demonstrated good reliability, too; the network was available at a reasonable and uninterrupted speed in 89.8 percent of our tests. Sprint's 3G network delivered a solid connection in 90.5 percent of our 13-city tests. Sprint's average download speed of 808 kbps across 13 cities wasn't flashy (at that speed, a 1MB file downloads in 10 seconds), but dependability is an important asset. The Sprint network performed especially well, both in speed and in reliability, in our test cities in the western part of the United States. The AT&T network's 13-city average download speed in our tests was 812 kbps. Its average upload speed was 660 kbps. Reliability was an issue in our experience of the AT&T system: Our testers were able to make a connection at a reasonable, uninterrupted speed in only 68 percent of their tests."
What have you noticed about the various carriers in your city?