Verizon has a faster network right now, but their customer service is horrendous and they are pathological liars. I will stick with AT&T until they roll out 4G.
Wrong....AT&T is much faster. Verizon is capped at 3.1 mbs......AT&T is now at 7.2 mbs here in Chicago. The 3GS supports speeds up to 7.2. You'd be going backwards if you went to Verizon and you would lose concurrent voice and data access.