Try stuff. See what you like. This is one of those "the bitterest fights are the ones with small stakes" arguments. No one can tell you better than you what is and isn't comfortable, and for every logical reason for x item, there's an equally logical argument against it. You'll go nuts trying to sort through everybody's contradictory bs.
BTW, I find cotton extremely comfortable and cooling. A lot of people do. That's why t shirts are go to summer wear for so many people.