Many good points have been made, and all are quite valid.

The 338 is far more practicle for a US hunter and is about perfect for an all around African plains game rifle. The 375 has the advantage of being legal for African big game. The 9,3x62 is is a wonderful caliber and has one big advantage over the other two...it can be made into a nice trim, light rifle.

I own each and would be hard pressed to have to choose which one I would part with. I think the 338 is the best choice if you don't ever intend to hunt African big game, only plains game and US types. You can always pull into Vern's Gas & Ammo in any town in the US and probably find 338 ammo.