Does it really matter?
I'd be more concerned about going with what works best for me. And quite honestly, in the average imagined situation, any of the three mentioned will work. I can handle all three.
More important than caliber chosen is the platform you decide to use. The platform has to be reliable. Very reliable. Second, you have to find a load that works it in it reliably. In other words, it has to be a load that functions consistently and is consistently accurate. No sense in buying a box of ammunition that's the latest "ultra/tactical/whatever" $35/per 20rd box if it causes your weapon to jam and/or isn't as accurate in the weapon as you like. Or causes more recoil than you can reliably handle. After that, you can bother with capacity. If you want/need more rounds without reloading, then go higher capacity. Just remember that capacity is never a substitute for reliability and capacity. A few things to think about, although they are my opinion:
1. Don't bother carrying if you aren't willing/ prepared to shoot.
2. Don't shoot if you aren't willing/prepared to kill.
3. Number 1 is directly related to Number 2. This is serious.
4. Carry only that with which you are reasonably certain you can stop a threat with. Face it, shooting to stop is a both a goal and an ideal. Killing is a very real and sometimes necessary result. Killing is also the most certain "STOP."
5. Not the last idea or comment (but the last comment from me on this post). There is nothing here that is an original idea from me. Literally countless people have thought of or said it before me. This is a small collection of opinions and beliefs of mine that is shared by others, the vast majority of which would be people I don't know and never will know. But it is something serious to think about amidst the ultimately silly "caliber wars."
P.S. Oh yeah, one more comment (sorry
). When it comes to the caliber wars, doing your homework is a good thing. Also, looking at data (that has evidence and/or is coming from a source you trust) is a good way to learn what the various calibers (and loads of said calibers) will or are capable of doing. Once you have this info, you can compare that with what you can handle and come up with a better idea of what you should be carrying.