It took burgers to lure me out of the shadows where I've been lurking, but as far as killer burgers are concerned, I've gotta go with:
Houston: Pappas Burger (I know, I know... it's not the same atmosphere of any of the Austin locations, but it's Houston). I'm starting to wonder if it's a coincidence that Pappa's B is right next door to Pappas Steakhouse (rediculously good steak)...
Austin: I've gotta give Huts the nod, but the lines are long and occasionally I've had a dry burger... Burger Tex is pretty good too (or the bulgoki option)... and rounding out the top 3 is probably a three-way tie between Crown, Posse (burgers not fries), and Dirty's.