I think it would depend on what a person wanted to hunt with those particular cartridges. While both are excellent rounds with distinct advantages and disadvantages, I would base the cartridge on animal I'm hunting and terrain I am hunting in. Bullet selection is much better in .338 than .366 In this regard I agree with Oregon45 if shooting longer distances with a 210 partition the 338-06 would be the way to go or the 200gr Accubond. It would be a great open country elk load. But when getting up in bullet weight there's no comparison. The 9.3 shines over the 338-06 in 250 and above weight bullets. For the bigger animals like moose and browns the 9.3 is my choice. One other thing to consider is finding a rifle you like in your choice of cartridges. CZ makes a wonderful 9.3 either in American style or shorter mannlicher. For 338-06 I think Weatherby might be the only commercial maker. There's always the custom route too. Either way both cartridges are proven performers.
