I prefer to carry my 3 inch .45 ACP, but it is not alway practical, so then I carry a Ruger LCP .380 loaded with Corbon ammo that is about 200 fps faster than normal .380 ammo. It fits nicely in my pocket.
Of course shot placement is important, but I don’t believe that one will have the opportunity in every self defense situation to make a head shot. Like for instance the perp has you on the ground beating you head on the concrete and you are struggling for the gun. I want something that is going to do more damage than a .22.