If I were you I wouldn't even go as hot as the .25-06 if you want it to be a good varmint rifle as well. Sure, the .25-06 is fine as a varmint rifle in terms of being able to splatter a groundhog or prairie dog all over the place, but the problem lies in if you plan on using it for any high volume varminting (prairie dogging and such). The .25-06 burns a LOT of powder for a varmint cartridge, which equals expense and barrel heat.

I think you'd be served well by a .243Win, 6mm Rem, or even a .257 Roberts or 6.5x55 Swede on the top end. If you want just a deer rifle for moderate ranges (inside 250 yards or so) the above would be good including the .25-06. A 7mm-08 or even another .308Win would also serve you very well and be more than enough for Texas whitetails. The .308Win would also serve admirably for bigger game like elk and even moose with the right bullets at reasonable ranges. As far as 1 MOA at 500 yards...it's a nice goal for a varmint rifle, but is it really necessary for a deer rifle. A mature deer has a kill zone of roughly 8" or more, and the average shot is realistically going to be no more than 300 yards anyway. You'll be hard pressed, IMO, to find a sporter weight rifle that meets that requirement without spending a truckload of cash on the gun.

Good luck,

Mike