Paul said it best. It doesn't matter where the property is as long as there is good positive cash flow. I'd pick Austin over Dallas and San Antonio. If you want reasonable appreciation, stick with single family homes.
Carol Ann Pease
I would stay in central or south central Austin. There are some pockets along 183 and MOPac that are good bets, as there are many employers and lots of shopping in this area so people want to live there. The thing is to make sure you get a reasonable price and that the property will create positive cash flow for you. Good luck!
Stick with single-family homes for the best appreciation possibilities.
Steer clear of areas that have new development very close by: these could hurt your rental property's potential appreciation.
I agree with Carol: single family homes or duplexes are easier to rent than multi-plexes. Property close to the university always leases, otherwise stick to the Hi-tech corridor on 183. Good luck!