I personally wouldn't have any of the WBY cartridges. Of those two i would opt for the 270wsm.
But for your application of a mountain rifle...
I'm thinking kinda for a mountain type rifle, mule deer, eventually sheep, goat, etc...but probably mule deer before any of those, and probably many more mule deer hunts than sheep/goat, etc...maybe on antelope too.
I'd look at the .260 Remington before either of the two you listed.