Which Cell Phone Carrier is best in specific locations?

The problem in snowbird areas is that the cell towers get overloaded at the height of the season. There's no way of telling which will be better and it can actually change periodically.

I carry both AT&T and Verizon and can definitively say neither is significantly better than the other. Some places one is better; other places the other is better. Even other places, neither works or both are great.

As said, roll a coin and flip the dice.