I don't consider "the hill country west of Austin" as "West Texas", unless you're talking about the western edge of the Edwards Plateau.
The biggest, most magnificent buck I ever saw was out in
real west Texas, somewhere south of Marathon, right next to the edge of route 385, back in the mid-80s. He was a Mulie, standing in the midst of a herd of Merino sheep. Easily 300 pounds on the hoof, probably more, with a rack with at least 9 points on each side, definite Booner. I doubt I'll ever see another buck like that one.
I searched around on the internet for a picture of a mule deer with a comparable rack. I'd say the buck I saw out there had one at least as good as the one in this photo (although his main beams were thicker at the base):
By the way, the best whitetail buck I ever saw was in Texas, too, but at the other end of the state...down near Beeville, in the southeast. And it had a rack that was about comparable to the rack on the mulie above, but clearly a whitetail rack.
Edited to add: To get to the question of the original poster, will you be shooting "suitcase deer", or big western mulies? For the former, just about anything will work, as long as you can shoot it well. For bigger deer, 30-06 is a good choice, because you can find ammo for it anywhere, and there is such a large bullet selection available in loaded ammo, that you don't have to take up handloading. Be practical.