The answer to that question is, all three are, when used within their respective ranges and proper bullet selection. I would have to say these three calibers are probably the most popular for big game hunting. Not to say there are not more calibers that are popular as well, like the 7 mm Remington Magnum and the .300 Winchester Magnum. For the ranges we are talking about in the deer hunting world, most shots under a 100 yards and say out to 300 yards. You don’t need a magnum cartridge with it’s increased recoil, just to say I shoot a magnum. If the ranges were to increase, then yes I would prefer the added punch of a magnum, or just get closer for a better shot. A few seasons ago I personally witnessed a hunter on a open pipeline on a buck doe day. He was sitting in a chair on the edge and two does came to the edge and stopped about 90 to 110 yards from him, he raised and fired. One ran across and the other, hit high and way to far back and now dragging it’s self across the open field. He fired again and now a gut shot, now he gets up and runs up to the animal and puts the barrel close to it’s head and fired one last round. So the point to my story is, shot placement matters more than fire power.
I prefer to use each round where it is best suited for. This is the break down that I use. The .270 for long range and game weight to 400 lbs., .308 for med. range and game weight to 800 lbs., and 30.06 for med. to long range with heavy bullets for game over 800 lbs. Not to say you can’t take an elk or moose with a .270 or .308, with a properly constructed bullet of sufficient weight and within reasonable ranges. I like using Barnes bullets for just about all my hunting needs, and Nosler Accu Bond bullets at ranges over 300 yards. Barnes bullets of heavier weight take up to much case space in these rounds and with the Noslers , the ballistic coefficient is much better for longer ranges and I can get a little bit more powder in the case and keep the pressures where they need to be. For minimum foot pounds of energy at point of impact on game, I like to use 1000 lbs for deer, 1200 lbs bear and bigger deer like Red Stag, 1500 lbs on elk and moose. Here is a ballistic chart of some of my reloads, loaded to near or at max pressures for my rifles. All of these rounds are so close to each other that game hit with either round is not going to notice the difference. Where it makes a difference is the heavy bullets, and that is where the 30/06 shines.
If I had to choose just one rifle round for hunting, I would have to go with the tried and true 30.06 cartridge. I can load light bullets at speeds over 3000 fps, for varmints and heavy bullets for bigger game like moose and bear. But for the non reloader out there, the selection is vast for factory loaded rounds for bullet weights and construction. Here is where I change my mind. If I had to pick one overall for hunting and target shooting, if would have to be the .308 cartridge. Since the .308 can use all the same bullets as the 30.06 with less recoil and as a reloader with less powder for target shooting. All three are capable of very good accuracy with factory ammo and even better for the most part with reloads, if the shooter does their part.
My last thought on this would be, why choose just one, have one of each and use them where there best qualities shine. Please feel free and tell me which one you like the best and why, and it doesn’t have to be one of these three. Have fun and be safe.