If I was choosing for heat tolerance, NN tops the list. I would also choose for a breed with a large, single comb to help dissipate heat, clean legs, slender build. Brahmas would be the opposite of what you want. Large, heavy, show type orpingtons, also, probably not so good. Leghorns, probably do well, polish, those things die if you look at them sideways I hear. never had any. Silkies, maybe too fluffy. Game breeds with racy profiles and tighter feathers. Cornish might be too heavy muscled and have trouble radiating heat, plus their small combs and thick legs. That being said, you could keep any of those breeds if you made a good shelter, start now growing shade plants that will cool their area, install misters, wet the dirt for them to wallow in during the heat of the day. A little effort and expense on your part, and you can keep pretty much any breed you want. If you want to go lo-tech, stick with the Naked Necks and Leghorns for starters. They will teach you what chickens want and need, then you can work your way into other breeds.