The Taco Cabanas seem to be sort of a luck-of-the-draw thing. Some are really good, and some are just so-so (but still thoroughly spank Taco Bell!). They were Texas-owned until a few months ago, when an East-Coast firm bought the local owners out.
I've had pretty good luck with the Chacho's chain, too. Kind of like Taco Cabana on steroids — They seem to be staffed by more experienced, non-minimum-wage people, and the menu is much more extensive — more like a traditional mexican restaurant's — except for the drive-through window and lack of any waiters to tip! Excellent nachos and breakfast tacos...
[b]ilikelegs[/b], is the Cantina Laredo still open on Beltline in Addison? They used to do a truly excellent plate of shredded beef enchiladas, but I haven't been to Big D in about 6 years...And, yep, as I recall, Herrerra's used to make a pretty decent plate, too!