A lot of good answers on this thread.
I'd have to go with the 160gr NBT out of my 7mm STW.
The OP did say one bullet, so why not also load that in the 7mm-08, and .280 AI?
The OP did sort of confuse things with his title to the thread "Pick One Bullet" when he might have meant one cartridge. I will say .308 caliber with a good 180 grain bullet in whatever cartridge can get it accurately out the barrel at over 2750 fps.
