I've been to both Chris Madrid's in San Antonio and Hub Cap Grill in Houston. Both are outstanding; quite frankly there are other burger places not on the list that are just as good; but probably none better. But most burger places are not as good. What I always care the most about are really good fries; something more along the line of what you get in Germany or France. Fresh out of the fryer, crisp and just salt, and a lot of it. There are more places with good burgers than with truly outstanding fries.
Quite frankly, it has been a few years since I have been to either. Hub Cap is just few blocks from the office and now would be a great time to go (mostly outdoor seating) before it gets really hot outside.
Need to go and check out the burgers and fries!