One key thing for guns is Armor Piercing (AP) ammo. The .308 Sniper Rifle + AP ammo lets you keep your distance and get the sneak shots, silencer ("suppressor", really) helps a lot.
I like to have a backup rapid-firing gun like a 12.7 or 10mm smg for when they get too close.
Strategy for where you are sitting really comes into play, too. Up on cliffs or structures where they can't reach = better.
You can melee & unarmed them with the help of some of the Knockdown perks, high stats, and good weapons. They have very long reach, so it ain't easy. I did succeed in killing one with Love and Hate, though it took 4 or 5 tries. :ahhh:
This, ammo and skill are what will do best against deathclaws..
Also adding to list..
12.7 pistol it's great against deathclaws up close.
Marksman carabine and AP or .223 ammo, this is a fast firing, medium damage gun that ignores DT with these ammo types.
Has a great RoF and is accurate and comes with a scope.
Hunting rifle and AP or JSP ammo, fully modded will be a great weapon to use.
As well as a trail carabine with .44SWC rounds, or a plain ol' brushgun.