Your question is pretty much open ended, but you defined parameters to pretty much Texas. A .308 is a good Whitetail Cal. It can be used on varmints with handloads ect. It would be at the top of its performance on Pronghorns or West Texas Mulies at range. With a 26 in bbl and good optics you can get a lot from it but I don't think it would outperform a .270 or .25-06 Its main advantage is it is easy to reload, rarely particular, and Ammo is usually plentiful. Also it can be accurate enough for a Target Rifle.

Top 2.
1 30-06
2 30-06

Can't argue with that.

#3 30-06

For what the original question asks, you could go with a 243, a 25-06, or a 270.

By universal, you mean best in the universe. That would be the 300wm.

I thought universal meant "Texas"...

The thing is, it ain't the headstamp that does the killing. It's the bullet. Which bullet, how fast, and where it hits is really the answer to all questions of this sort.

How fast depends on that headstamp.

If God had thought the 30-06 was the best overall cartridge, he wouldn't have created the .270.

308 doesn't even make my top 10 list but the 270 dang sure does, it's a very versatile round.

Me too. I have a .22-250,.243,.257 Wby.,.308 and .300 WM. But 98% of the time I pick up my .270. Kinda the definition of "all around" rifle to me.

OK - That's funny. I'll give you points. I do own a .270 and hunt with it often.

However, I will stand firm that the .30-06 is very versatile. You can buy a very large assortment of loads off the shelf. With handloading you can go from big-bang to small loads for varmint hunting. It is widely available, relatively inexpensive compared to less-popular rounds, and is extremely effective.

I'd go with a Remington 700 in .30-06 all day long.

To me the 30-06 is useless. I have one and haven't shot it in 12 years. It was my dads first rifle. Old spring feild he hand made stock for so ill never get rid of it. I just don't see the point of it since the 300win mag can do everything thing the 06 does but better. Its funny he gave me the 30-06 after he got a 270

270 great round, I just prefer the 257wby over it. Now the 270wsm is a whole other level kind of like 30-06 vs 300win.

Not like we need huge caliber to kill deer in tx... mulies or whitetails.

Oh, I have a .270 WSM too and actually think it is just about the perfect caliber. But it is a light mountain rifle so that's what I use it for.

Really, anything from .25-06 up through .300 WM/WSM is a good answer to his question. And we all know it. We are just mostly stating preferences-as always.

i think most of it would fall back on shot placement and the type of bullet used.
its hard to beat a 25-06,270 or 243.
good luck with your choice

All around, I would choose an AR in 6.8x43 with good barrel for my particular situation which is mostly woods with up to 250 yard shots.
I have other guns that excell at a single purpose better but fall short in others.

As to the AR:
With good barrel/components, it's as accurate as you are.
Enough knockdown to take anything in Texas - and how often do you shoot over 300 yards...
Not effected by rain or a complete dunk - for weeks or months on end - don't try that with a blued steel/wood stocked gun unless you like rust and warped wood.
Light weight unless you bolt on every tacti-cool accessory you can find.
Rapid fire power if/when needed.
It's modular so you can change it if you don't like something.

One registered lower and multiple uppers and it can be anything you want - kinda like an Encore but with rapid follow-up when needed.

No love for the 30-30?

Just the Eastern portion...you can kill everything else in the state with a bottle of water and a rope.

Any of the 300 Mags especially the 300 Win, and 300 Weatherby will out perform most hunting rifles at about 550 yards on. Of course one could go exotic and use a 338 LaPua or 408,416 Che Tac and then you get out well past 1000 yds which also would eliminate sure humane kills. I'd think the rifle would be whatever the individual shoots well if quality ammo is used. Even with a large Magnum Rifle if the projectile performs poorly or the Hunter makes a poor shot the animal may escape suffer or be lost.

Did someone say 30-06 !

Sorry, too inconsistent accuracy regardless of platform.
Btw, I would probably go 25-06 or 243 given the original parameters.

Call me a sucker but I still like reading this, what if u had only one caliber?" questions.

The answer to the "if you only had one" question is easy: .300 WM.

I'm pretty sure he wanted something that wouldn't destroy a coyote or bobcat. That means less velocity. I have killed a pile of deer and hogs with a Ted Williams Model 100. Perhaps the best would be a 7-30 Waters.

220 swift or 22 hornet.....

Also, I'd like to add to my answer for everything: 270/30-06. You can get 95grners if you look hard enough and 220grners(30-06). Lot of versatility there. At least with a 270