What is the freshest material for custom seat covers?

I'm about to buy custom seat covers for my 2004 Honda CR-V. Since I live in the desert, I'm looking for the material that would be the most comfortable and fresh possible.

Added (1). Please, forgive my mistake. I meant "Cool". We have temperatures in the 110's during the summer, so I'm looking for the most comfortable option possible temperature-wise.

"Fresh"? Please explain. Do you mean "cool" (to the touch), the material that can most effectively dissipate heat?