Saying who's BBQ is the best simply cannot be done. BBQ means different things by region.
Here in Texas BEEF is king. brisket, beef ribs, and sausage are staples. Acceptable sides are slow cooked Pinto beans and potato salad. Ideally though, a good brisket, with fresh onion, pickles, and a slice or wonder bread is all you need. Sauce is optional, but good BBQ does NOT need sauce.
I'd agree that Blacks or the City Market in Lockart. In Elgin I've had Southside Market and it's good. I friend of mine spent soem time in El Paso and he suggested State Line. I personally haven't had it as I only stop in El Paso for gas.
Do not sell yourself short though. Tex-mex food down here is to die for. Be sure to hit a few of those while anywhere in the state.