Austin is okay but I would never live there; it's just a little off base.
Houston is just too freakin huge for my taste. I lived there for a couple of months and it just wasn't my speed. I've never been to the DFW so I can't weigh in on the metroplex.
I'm a San Antonio gal. To me, SA still has that small-town feel. With it being the beginning of the Hill country, it's location is also perfect. It's 2 hours north of Corpus, an hour south of Austin, and only a 3 hour drive from Houston. The weather is perfect. There's tons to do. You have all the sports, museums, shopping, theme park, golfing, etc. If you're interested in continuing your education, there are 4 private universities and 1 public.
Check it:
http://en.wikipedia.org/wiki/San_Antonio,_Texas