from a tactical/survival/HD standpoint i would have to agree with
some type of Scout Rifle in 308cal with good peep sights and a scope would be the way to go, or if you want a sniper rifle some type of Varmint rifle in 308cal with a good scope would be the way to go.
however if you have a good sixgun in say 357mag, 44mag, or 45 colt you could have one of the marlin lever action's in the same caliber which would mean you would only have to carry one kind of ammo.