Either the .270 or .30/06 would be fine. They’re the same cartridge except for bullet diameter. Most experienced hunters consider the .30/06 to be more versatile, as you can buy .30/06 ammunition with much heavier bullets than any .270 ammo. An old-time gun writer named Townsend Whelen once said, “The .30/06 is never a mistake,” and after hunting with the cartridge on three continents, I agree completely. Any 180-grain .30/06 factory load should work fine on deer and boars.