RE: 30.30 or 30.06
I have a 30-30, and it'll kill deer just as dead as anything else. The area I hunt has very few places you can see far enough to even need a scope, much less a bigger gun. It might not work so well in other areas. The .270 seems to be a pretty popular round around here for most deer hunters. It works better for distance shots.
Where in Texas are you going to be hunting?