I've got three derringers, .22lr, .38spl., and .45acp, I tried to check all three but the poll wouldn't let me.
As to the question, "What would I use?" I have carried all of them at one time or another, and some times I have carried two of them at the same time.
I worked, part time at a gas station, back in the '80s, and always had one of the center fire ones in my pocket, I knew most of the customers that would come in on my shift, but when a questionable looking stranger showed up, my hand was in my pocket,the gun was ready to draw and fire if needed.