RE: .270 or 30-06?
I would definitely say the .30-06, both in merit and matter of opinion. With the right ammo and shot placement it can be the most versatile rifle you could own, able to take all big game in Texas, exotics included. I do, however, believe you could handle either calibre, but the .30-06 seems more conducive and practical. That said, I too am biased, it's what I use on big game in North America. I'll just say that you would not be making a mistake in opting for the .30-06 - if you get a full, not youth, model, you will be able to use it on any hunts you go on in the future (with the exceptions of elephant, cape buff, leopard, and some other rough-n-tough game).
Best of luck,
Kimberly