When testing speed recently among the four wireless carriers in my area -- Cingular Wireless, T-Mobile, Sprint Nextel and Alltel -- I used a phone from each carrier with a subscription to a data plan as well (for laptops) to give as equalized a result as possible.
So, which carrier turned in the performance to the right? Let me state that Cingular and T-Mobile both offer EDGE speeds in my market (no HSDPA yet), and both Alltel and Sprint Nextel offer EV-DO speeds in my. Not sure about testing HSDPA speeds since Cingular has not rolled that out yet in my market.
The winner? Sprint Nextel's data speeds were the fastest (17% faster than Alltel and about 600% faster than both EDGE systems) -- as I received almost a megabit if DL speeds on the Sprint EV-DO network, with a little over 1/10 of a megabit in UL speeds.