[2.7RACER]

Back to the original question;"what is the best semi-auto pistol caliber to have in time of crisis?"
As pointed out by so many here the "best" is a hand gun that you have practiced with and have become familiar with the operation of the handgun.
So many semi-autos, even the high dollar ones, don't work with all available ammo.
I have seen so many jammed hand guns at the range along with people not even remotely familiar with gun handling.
One reason the police usually prevail in any kind of shootout is "PRACTICE"
The bad guys die when confronted with an armed person familiar with their hand gun and some tactical training.
To answer the question; "the best caliber to use in times of crisis" is one which you have PRACTICED and TRAINED with.
Nothing beats practice, practice, practice and training.
Once you have made the decision to own a gun, you have taken on the AWESOME RESPONSIBILITY to use it only when absolutely necessary, with the TRAINING and PRACTICE to use it well.
An aside, don't forget to keep your guns away from children, preferably locked up.
At the range the question often comes up "what is best to protect my home"? answer? A large dog.