Civilized world and desert: heat. Nothing beats being totally open to a nice coastal California or Mojave sun in the summer, and even in nastier desert areas microbial/parasitic contamination is pretty rare.

The South, other third world areas, and tropical environments: cold. I don't need to deal with the South's mosquitoes or Missouri's ticks and the diseases they carry, not to mention all the digestive thrill-rides that proliferate in the heat in water treated by third-world sanitation tech. Plus, violent crime drops with cold weather, which is nice as these regions tend to have higher population density.