I think most all of the calibers mentioned, .38, .357, .357 Sig., 9mm, 10mm, .45 ACP, .44 Special (which I don't think anyone mentioned, until now, as well as the new .327), will all do the job. The unknown variable is at the other end. Some folks are going to fold like a house of cards hit in the arm with a .38. Others will be like the guy at the infamous FBI shootout in Miami that led to the development of the .40 caliber (10mm Weenie). How many times was he hit before he finally went down? (I have forgotten.) You can talk about "one shot stops/kills" all day long, but the tricky part is the person being shot. And I'm not even talking about PCP or any other kind of drugs in his system, I'm just talking about a regular person. We're all different. Too different obviously for anyone to set in stone that their favorite round is going to drop someone first time, everytime. That's why we shoot until the threat is nullified. Man, pit bull, or angry squirrel.
(I better add .380, .41 mag and .45 Colt to my above list so no one feels left out. I did omit the hunting rounds and the real weenie loads on purpose.)