Oh man, where to start..
Texas--Whataburger (we have some in Florida now)..gotta get that japaleno burger. I realize Chuy's is not fast food, but I love that Tex-mex chain and try to eat there anytime I'm in a city in Texas that has one.
NC--Bojangles. A Bo's sausage biscuit and iced tea is a great way to start a summer day.
I always stop at Tim Horton's while in Buffalo for coffee and timbits.