as SsK said....Whataburger is the shiznit!! you can get regular food or breakfast food. couple of potato, egg and cheese taquitos will do you right every time!!
second favorite would be two pesos/taco cabana. soft tacos, flour tortillas and queso, etc...mmmm!!!
Texans know whats up...a double meat whataburger with cheese and jalapenos, toasted buns on both sides with a sprite easy on the ice! the A-1 Thick and hearty is a doozy as well! but the key is getting the buns toasted on both sides...once you do that, you wont want it any other way, TRUST ME!