[Jack]

Other posters have quite validly pointed out that the specifics of what load is used in any caliber makes a lot of difference.
Beyond that, the 'stopping power' field is full of opinions, and not a lot of facts. There are all kinds of formulae out there that were derived by someone who already knew what answer they wanted, and set up a formula to suggest the formula writer was omniscient.
One actual fact I will bring up: expanding ammunition for handguns has improved to a startling degree in the last 20 years or so. 30 years ago (give or take) soft points and hollow points in handgun cartridges often didn't expand. That's according to me shooting them into a bunch of different test medium, so, you may have a different opinion. Handgun ammo today, a lot of it, actually does expand like the makers say it will, and quite consistently, too. Again, my observation.
The only advice I'll give on the subject of what's best is: pick a firearm you have confidence in, and practice a lot. Only hits count. You can have the newest, fanciest, most powerful, loudest firearm in the world, and if you miss with it, it does you no good at all.