There is much debate about which caliber is best for defensive purposes and is you post a question comparing calibers performance it will no doubt lead to a "caliber war". I'm not sure why, but people tend to defend their choice of caliber like it's one of their children.
Between the "big three"(9mm,.40 S&W & .45 ACP) pistol caliber choices,there truly is very little difference among them if high quality, appropriate for the situation, ammunition is chosen. So, lets look at the three basic things that make for an effective shot(s).
1.PLACEMENT......Shot placement is crucial when it comes to defense shooting.A hit with a .380 is much more effective than a miss with a .45 ACP. And WHERE you hit is just as about as important as well.Even a 9mm will kill a Grizzly Bear with the proper shot placement.So,make sure you place your shots where you want them.
2.PERSON.......We are all individuals and skills/abilities will vary from person to person.It's so much always the gun or bullet itself, but the guy who is wielding it. Just as it isn't styles of Martial Arts that fight, it's people.
3.PIECE..........Meaning the actual gun("piece") as well as caliber/bullet you chose.If you pick a gun that is too big for your hand or has so much recoil that it nearly breaks your wrist,then that gun will not serve you well in a defense situation. A gun that fits your hand well allowing a good sturdy full grip on the firearm and optimum trigger reach in a caliber that you can control & shot well allowing for follow up shots.You must also look at the bullet itself.Use only ammunition from reputable brands such as Federal,Winchester,Remington,Hornady & Corbon. Use good quality Jacketed hollow-points since FMJ's have been shown to be poor performers(even in .45 ACP). About the only time you would not use JHP's is for Hunting or Large Predator defense since you'd need the extra penetration and you probably chose a caliber other than what's common for defense against Humans. .38 Special,9mm,.40 S&W,.45 ACP are the most common and generally recommended calibers for defense against people..380 ACP could be included as very bottom acceptable,but is very marginal IMO. 10mm is also an option,but hot loads can over-penetrate and endanger other people.If you use 10mm for defense against Humans,then it's probably a good idea to use "10mm lite"/10mm FBI loads which are equivalent to .40 S&W.
Hot 10mm & .357 Mag are the minimum recommended starting points for Hunting Handgun/Large Predator Defense..44 Mag is more commonly recommended, but if you can't hit with it or follow up,then a .357 or 10mm might be a better choice. A 12 Gauge or high powered Rifle are even more effective, but cumbersome,so many people don't like to carry them and unless you carry the Rifle/Shotgun in a ready position,you may never be able to reach it fast enough.A handgun is much quicker to bring into play against a surprise run in with a Bear than a Rifle slung over your shoulder. A Glock 20 holds 15 Rounds of 10mm which would be comforting IMO in the backwoods against all predators two or four legged. The G20 is a favorite among many Alaskan guides who carry it for Bear Defense . A Glock 20 with a canister of Bear Spray held in the Harries Grip should be pretty potent combo even for a grizzly. Just a consideration if venturing into Bear Country.
Bottom line is choice of ammo selection has to be use/need specific.