Since you want to be able to use it for elk, I would get the 30-06. The 308 or 270 would also do double duty but the 06 would be a slightly better choice. If money was not critical I would pick up something like the 7mm-08 or 260 for deer and buy a elk rifle if you ever really need one. Its nice to have a deer rifle thats comfortable to shoot and something you can enjoy using. To much recoil is just no fun IMO.