I would say that a .270 would be a great caliber for a deerhunting specific rifle. You listed some manufacturers that make good products and not likely to go wrong with any of them, so I would do some "hands-on" research by handling them and shooting if at all possible and then pick one. As far as lasting a lifetime, pretty much any firearm will last a lifetime if taken care of properly. You may end up needing a new barrel or something at some point, depending on how much you shoot, but likely little else. Good luck in you decision.