For Brisket, post oak is what you would find in the Lockhart area
For me, I've found Oak and Pecan to be great for ribs/brisket...but this is like most of BBQ and it's all really opinion and experiences without one "right" answer.
Basically...cook a lot of ribs and briskets and vary the wood and see what you' like best
Always was happy with post oak till I was clearing some land about 10yrs ago, and we pushed down several hickory trees. Much of that wood was saved exclusively for BBQ use, and it's our favorite. But can't go wrong with oak or pecan.
Mesquite is the hottest burning wood in Texas (if not the US) only Polynesian Mango(or papaya) burns hotter to my knowledge.
This is why I use it in our pizzä oven. This and I can get it free if I do the clearing. Any excuses to play with a chain saw and ax is a good time to me.