Seems that sometimes variety is King....
With all the panic (or insight) buying, that owning a variety of self defense weapons is the best option.
With imposed 2-Box limits, etc owning one caliber self defense weapon would be a poor decision.
As posted, I've added two 9mms this week. I also own a Ruger 9mm PC Carbine. I don't think it'd be a poor choice for defense around the home front.
ARs always get the most hype. But, I think the Carbines in pistol cartridges would be a good choice.
Owning 9mm, 38 Super, 357 Sig, 40 S&W, 10mm Auto and 45 acp is a good idea. Could utilize about any ammo you could get.
Even some spare barrels for Glocks in different calibers wouldn't be a bad idea.
At the end of the day, a Ruger 10-22 would be better than throwing rocks.