My vote:
1.Sammy's BBQ behind the Federal Reserve building in Dallas.
2.Coopers in LLano or Junction. BEst pork chop ever.
3.Rudys in SA on I-10W at Leon Springs.
I often drive to Llano from SA just to pick up the BBQ at coopers. And as another poster suggested, I have flown there with private pilots. When I was taking flying lessons, I would do my cross country's from LRD to Llano solo just to get the BBQ.