Coming from a former AT&T Wireless/Cingular employee, I'd go with Verizon. Part of me feels guilty for most of the family being on Cingular/ATT. I had my own, free employee plan. I also activated my wife and my parents on a discounted, $10 dependent line (ATTWS plan). So because my wife had AT&T, her family started getting AT&T also for the free mobile to mobile. There's a large, AT&T/Cingular call center here in Cerritos, CA and I always found it funny and ironic that even in our own building, we got poor reception.
Pretty much most people at the company knew that if you want voice quality, you go with Verizon. So ATTWS main goal was to win in customer service. Unfortunately, the Seibel 7 upgrade that took down our (GSM) system for months happened during Xmas season and the federally mandated line number porting also happened at the same time. It was a double whammy for the company and instead of trying to fix their problems, the CEO, John Zeglis, was more looking to just sell off the company. He was getting millions anyway, who cares if he screws up the rest of the company. ATTWS was #2 before all this and had possible plans to buy out Sprint, Cingular, or T-Mobile to compete with Verizon's customer base. We all know how that turned out.