I use
Sprint CDMA
DC/Baltimore Area

Verizon GSM definitely have the better coverage but I get a good signal from FL to Vermont. Its just that there are more pockets that you will drop you signal with Sprint. I have noticed that has been getting better. Areas that I wouldn't get a signal before is fine now. But if you are in a metro area all carriers are solid (as far as a cellphone can get). Though i did have some issues with ATT in DC.

It is true that CDMA is faster (though the browers still sucks) but the speeds aren't noticebly different. With that said....I went with Sprint because they had a better data plan not really the speed.