I'm a little north of Dallas, and on my third year of chickens. It's so hot here that any breed will suffer some in the summer so be prepared to take measures to keep them cool regardless of what you get. Some things were mentioned above and every summer there are threads in the main forums (Feeding & Watering, or coop design or managing your flock).
But your question was about breeds that handle the heat better. I agree about Mediterranean breeds in general. I've had good luck with Leghorns and Catalanas. Leghorns lay a little more, but the Catalana eggs are just as big. Leghorns are a little more skittish, Catalanas aren't exactly cuddly but are a little more approachable. You probably want to avoid the breeds with really heavy feathering, feathered legs & such, although I have a Brahma who's doing fine this year.
And consider Naked Necks/Turkens. I have 3 of them, and 2 of them are very friendly - will jump on your arm for scratch. The other is not so friendly but I do manage to pet her occasionally. And they only have half as many feathers as regular birds, but still handle the cold fine (I don't know where in Texas you are, but mine handled the "Super Bowl Storm" this year with no problems in spite of fewer feathers and large single combs. At the same time, my Production Red rooster - developed from RI Red and New Hampshire Red - got a teensy bit of frostbite on his comb tips, despite being a New England breed.)
On the other hand, I also have Ameraucanas, Plymouth Rocks, and Buff Orpingtons (until predators got the BOs) and they have also done fine. They and the Brahma are not as active, though. But they get their foraging and running around done in the morning, I really only notice the difference in the afternoon.
Hope that helps!