Houston is ok, if you like continous suana like weather. Humid, hot,..then cold and humid.
Austin is a nice area, but during some parts of the summer it can get pretty miserable due to the lack of wind in a lot of areas (hills and valleys abound). Cannot beat the lakes around Austin. They are absolutely the best.
DF/W (Dallas/Ft.Worth) is a bit unique. Two cities which have very different cultures and lifestyles. Dallas wants to be a New York type of city. The hustle and bustle and fast pace (well,..fast for us Texans) directly contrast with Ft. Worths mild mannered slow Southern style and pace.
Between all of the them, I think it is easier to find diversity in the DF/W area. And the world-class airport makes it easy to plan trips to just about anywhere on the planet.
One constant; Texas (not transplants so much, nor Bubba when he is on a beer binge,..or worse,..when Bubba is outta beer) folks are about as friendly as it gets.