alot of these choices I'm seeing here I don't really consider "fast food". To me, anyplace that you have to sit down and order off of a menu isn't fast food. I like the Pappas restaurants but I don't consider them fast food.
That being said, for Houston, I like Taco Cabana for TexMex fast food.
I like In N Out Burgers and wish we had them here in Houston. I do make it a point to go to In N Out whenever I am in Las Vegas or anywhere on the West Coast that has one.