Which Cell Phone Carrier is best in specific locations?

It seems that Verizon has chosen to go for wider area coverage, while AT&T has opted to focus on population centers. For camping, and now that we live in the West, Verizon is the way to go. It doesn't cover every area, and even at home we have issues as the tower(s) are "over the hill" from our house, but they are still the best game in town for less populated parts of the country.