Do you want to keep things simple or entertain a little more work? And, what exactly are you planning on using it for?
One simple gun only, that is overkill on a lot of stuff: I'd go 338 Lapua. You get the best brass and a bigass bullet and there is no other caliber that can champion it to any real noticeable margin, IMO.
You want some pizazz? 338 Edge, one of Kirby's calibers, 338 Lapua improved...
You want anything in between: I'd go 300 RUM with a 210 Berger VLD first. I cannot think of much of anything this won't handle.
There are way too many choices.
If we were next to each other shooting at 2 elk at 950 yards, I'd be just as comfy with my 7mag and a 180 VLD or my 300 RUM and a 210 VLD even if you had any 338 configuration. And, I don't think you, the elk, nor I would be able to say something is more lifeless than the other.
Picking one gun is just like picking one woman. She's out there somewhere, just start grabbing some tush and see which one cranks your tractor, because she's got to handle every situation you want to put her in.