The only question that has not been asked, is: To what range will you limit yourself on elk. I have talked to a fair number of elk and moose hunters who swear by the .270Win. as a great killer of those two game animals. To a man, they are hunting timber and not taking long shots. If you know where to place the bullet and have the right angle, no doubt, the .270Win. is a fine elk rifle. On my elk hunts, ranges can be long. I mean 300-400 yards is *my* long. For that range, the .270Win. is not a good choice. Hey, don't get me wrong, I love the .270Win and have taken white tails, muley and pronghorn with the .270Win. But when I believe that I may have the chance at a long shot on elk, I want something that will get there with plenty retained velocity and energy, so that it can make a big, deep wound channel. Now, we need to address how much recoil you can handle and how much you are willing to try various loads, before you hit on the best fodder for one of those magnum cartridges. The field is wide open. Like somebody already mentioned, most all centerfire rifle/cartridge combinations will kill elk DEAD.
For what I want right now, given that I am will hunt west central CO., the 7mmWSM is the ticket. Reasons: great accuracy, fairly light rifle, 24" bbl, no brake, can take advantage of the newer premium bullets, a proven elk killer.
Pay as much or more for the optics, as you paid for the rifle. Get the best mounts and rings that you can find. Get to the range a lot, before taking to the woods for elk.