What is the best defensive round for a concealed carry handgun?

gomakemeasandwich asked:

Just interested to see what everyone's thoughts are on the best defensive round for a concealed carry handgun. 9mm? 40 cal? 45? .38? .357 Magnum?

Also, what type do you think would be best? Revovler or Semi-Auto?
"Personally, I carry a .357 revolver..."

Good points about the revolver, but isn't round capacity a serious limitation?
I should clarify: I'm looking for the best cartridge, not the best manufacturer.
When you state your answer, please include why. Thank you.

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