I voted .300 Win Mag but it wouldn't be my first choice. I'd rather have a .30-'06, 7x57, 8x57, .280 Rem or some other "all-around" caliber. If I had to have something on belted, magazine-space-eating brass I'd probably pick .338 WM as my first choice.

The 300 H&H would be a classic selection, but I rarely handload any more and can't justify the high ammo prices for performance I can get out of my '06.