One of the challenges about planning for SHTF, is you still need to live your life the other 99.99% of the time when the SHasn'tHTF.
So you'd want a dog who would be a
-great family member
-natural guard dog
-long ranged, solid, semi-independent hunter.
-eats just about anything.
-doesn't shed much at all, and is virtually odor free (hey! my wife hates dog hair)
And you get a.... Rhodesian Ridgeback.
100 lbs of solid muscle & bone. Fiercely loyal, without all the overbreeding of aggression of pitts and rotts, and way more structurally sound than GSDs. most RRs can live at least 10-12 healthy and sound years.
This is a combo sight-scent hound, with a lot of independent thinking. He's not the best at any one thing, but they were bred to guard the family farm, corner dangerous prey for the hunter (a pack of RRs will trap a lion), alert the family of intruders, and play with the children..
Our 12 week old puppy is great at playing with the kids, I'll let you know about the other factors as he gets older.
Regards,
Francis