During March and April, we spent a day testing the major 3G services in 13 cities across the United States. Verizon's service showed a combination of speed and reliability, Sprint's results lent credence to its 'most dependable' claim, and AT&T's network showed fast upload speeds in most cities.
via pcworld.com
As an AT&T subscriber, I'm completely unsuprised that AT&T's network is less reliable than Sprint & Verizon. I would have been really curious to see how T-Mobile's network stacked up.