A rational thought exercise for you.
You have a 9mm EDC pistol, a .22LR rifle that takes mags or drums and a .223/5.56 AR15 rifle. If you can only stock up on ammo for ONE of them, which is the most advantageous to prepare for a SHTF survival scenario? Most importantly, WHY do you choose your particular ammo?
Looking forward to your responses, especially from you seasoned preppers. Let’s make your budget $500.
I’ll start by suggesting .22LR, because I can buy the MOST ammo for the money. It can be used for small game. It is easy for wife to get comfortable AND proficient using. While not optimal, it can be used for SD, especially with a 25rnd. mag.
I agree with Ron43xMOS, except the wife part, she won’t touch a firearm.
Please get a little more specific with the types of weapons we have.
Is it a 9mm pistol or a 9mm Carbine? I have both as EDC’s.
Is it a .22LR pistol or rifle?
Is it an AR15 pistol or Carbine? FYI, I don’t own a weapon in an AR platform at all.
Electric, water, food, fuel are all scarce. She may think differently when pressed to survive. (My wife won’t go near mine either.)
Your EDC is a PISTOL. .22LR is a rifle. AR is a rifle. Original post has been clarified, thanks.
You and Joseph161 need to trade your Wife’s in on different models. My Wife is a genuine peace-loving hippie, but she still has her own weapons. She is also a practicing Witch, so run for cover when the spell book comes out.
Trade in’s not an option after 41 years. High mileage. 
I’ve gone through pretty much this exact thought exercise, and stocked up on 22LR. I can buy thousands of rounds for dirt cheap. I have an ultra reliable rifle and revolver to shoot it with. I can carry a lot of ammo with minimal weight. Firing it doesn’t loudly report my location for miles. It can serve a defense and food gathering role. In a true SHTF situation, the bigger game will all be dead in days, I’m figuring, and survival will mean eating squirrels and rats and whatever else I can shoot and cook quickly. And, again, it’s cheaper than any other cartridge, by far.
That being the case, I would choose to stock up on AR ammo, either 5.56 or .223, whichever mine is chambered in.
The biggest reason would be that I can store it all in magazines ready to use when needed. While there are a few .22LR rifles out there using detachable magazines, most of those magazines are low capacity. My Wife’s trusty Marlin Model 60 has a 15 round tube magazine and it is slow to reload. If needed to be used in a battle type situation, there would be a long interval between having your weapon out of battery and then back into battery to continue the fight.
I am a new shooter with hand and arm arthritis issues. I find this offering from Henry Repeating Firearms intriguing. One of my instructors stressed the importance of being able to shoot with the weak hand/arm if injured in the other. Recoil is my main issue with firearms, so it seems to me this would be almost ideal for those of use who have to deal with some type of injury. Advice welcome (also on ammo type?).
I feel you on this one, Brother. May as well just keep her. 
I have known my Wife for 27 years and have been with her for 25 years. I met her when she was 18 and still married. She saw the error of her ways and dropped him like a bad habit. He even had the audacity to tell her she could own any firearms in Texas because she wasn’t born here. What an A**.
Like grandma’s undergarments, Depends.
Are you in the country or the city? Suburbs or farm/ranch?
Mountains or desert?
Bedroom community or city?
Big city or small town?
In survival mode I would take the 22 rifle as well best for small game for food. Also the ease of carrying a poopton of rounds. Plus with new ammo like the Stanger they provide acceptable human stopping power.
But if is about survival and equally protection from human predators I would go with the 223. I’ve had perfect head shots on grouse with 280 REM, so you can still take small game.
I think the Ruger 10/22 is probably one of the most common .22 rifles out there. You can easily get 15 and 25 round magazines for it as well as a 50 round drum option.
Okay, let’s assume you have a .223/5.56 AR, and the .22LR rifle can take several mag sizes, up to a drum.
Original post is updated, thanks.
That’s a good .22LR option. Tried and true, and built for survival. The 8 round mag capacity was a bit anemic for my liking , so I opted for a 10/22 Takedown with 25 rnd. mags, albeit at the cost of an extra 1.1lbs of weight.
Let’s just say, given the three choices, which ammo choice would be best in an overall utilitarian sense. (The best choice for most people, not necessarily just your specific region) Trying to keep it simple, thanks.
.22LR and here’s why:
Not for defense although it might be better than using your fists.
Not for hunting although it can suffice for small game, if here is any.
For practice/training.
Save the more powerful stuff for if and when it’s needed.
My 2 cents anyway.
Ok, I’ve updated the original post to a limit of $500, just to make it a more interesting scenario. Thanks.