My first choice is my Sub-2000.
9MM, damn accurate, short enough and light enough to get around with, will not blow through three walls and kill my neighbor like my 5.56 could.
I see it as a better choice for me because it folds easily under the bed, weighs next to nothing, deploys quick and easy.
With 600 lumens glaring out the front end, I will see, hit, and most likely stop whatever threat even half asleep.
Using my handgun I would stand little chance of doing anything short of scaring whatever the threat is to death.
SHTF, or other survival situations, I would bet on my AR15 in more open environments, the subbie would be used for cleaning buildings something like it. I cannot imagine what it would sound like to pull the trigger on that AR in a room with no plugs in
I also cannot imagine anything living that would stand back up after a hit from that 9, I would bet the average burglar is not wearing body armor...