6.5 inch SS single six.

Pros:
.22/.22MAG
.22 is easy to carry
I can hit a 16inch plate supported at 100 yards
.22 is not a joke when you can actually hit vitals
versatility
simple mechanical function
barring ammo quality, if the hammer falls it will go off.
It is stainless steel
It is relatively light
it has adjustable sights.
I can switch to Magnum for a quick 6 mor rounds.

In SHTF I do not plan on getting into a firefight
In SHTF I want to evade
In SHTF if I am not at home I am in big trouble anyway
In SHTF I want the best bang for the pound not neccesarily the biggest.