RE: Pick Two
.25-06 and .338 Winchester Magnum. The .25-06 is good from coyotes to pronghorn antelope to white tailed deer to mule deer to sheep to caribou(a bit overgunned and loud for prairie dogs, perhaps, but it will get 'er done nonetheless). The .338 Winchester Magnum is good from mountain goats to elk to moose to various bear. If you think .25-06 is too light for sheep -- I don't think that is the case -- you can use the .338 Winchester Magnum for sheep also.