Hopefully these graphs render ok.
From them you can see that 40 S&W can match 9mm for velocity and 45 ACP for energy (depending on load).
With 40 S&W you get better magazine capacity than 45 ACP, and about 85%-90% of the capacity of 9mm.
Ammunition is less expensive than 45 ACP, and not much more expensive than 9mm.
There is the advantage that 40 S&W is in wide use by LE, so ammo will be widely available.
If I were in combat, I would choose 9mm for the slightly greater magazine capacity, and if I needed something to suppress (sound), I would choose 45 ACP since it is subsonic (without load modification). If money and over penatration were not concerns, I would choose 357 SIG, since it is clearly the fastest, most powerful load. As none of these is the case, I chose 40 S&W for its balance and versatility.
For what its worth, I own pistols in 22lr, 380 ACP, 9mm, 357 SIG, 40 S&W, 10mm, and 45 ACP, but I choose to carry one of the 40 S&W pistols. I carry the 180 load, which has better organ depth penetration than 45 ACP and better permanent wound channel creation than 9mm.
All that being said, I would probably feel comfortable carrying anything 380 ACP and above, and would not want to be shot with anything at all.

Here is the table this is based on. This is for Gold Dot ammo, which I chose, because it passes both the FBI hard surface and IWBA soft surface expansion tests.
Load MZ 50 100
9mm Luger 115gr 1200 1065 976
9mm Luger 124gr 1150 1039 963
9mm Luger 147gr 985 932 887
9mm Luger +P 124gr 1220 1085 996
357 SIG 125gr 1375 1203 1079
40 S&W 155gr 1200 1063 974
40 S&W 165gr 1150 1042 967
40 S&W 180gr 1025 956 902
45 Auto 185gr 1050 955 886
45 Auto 230gr 890 845 805
45 Auto +P 200gr 1080 994 930
Load MZ 50 100
9mm Luger 115gr 368 289 243
9mm Luger 124gr 364 297 225
9mm Luger 147gr 317 284 257
9mm Luger +P 124gr 410 324 273
357 SIG 125gr 525 402 323
40 S&W 155gr 496 389 326
40 S&W 165gr 484 398 342
40 S&W 180gr 420 365 325
45 Auto 185gr 453 375 322
45 Auto 230gr 404 365 331
45 Auto +P 200gr 518 439 384
Load 25 50 100
9mm Luger 115gr 0.8 3.5 8.3
9mm Luger 124gr 0.9 3.9 9
9mm Luger 147gr 1.5 5.5 12
9mm Luger +P 124gr 0.8 3.3 8
357 SIG 125gr 0.4 2.3 5.9
40 S&W 155gr 0.8 3.6 8.4
40 S&W 165gr 0.9 3.9 8.9
40 S&W 180gr 1.3 5 11.2
45 Auto 185gr 1.3 4.9 11.1
45 Auto 230gr 2 7.1 15.3
45 Auto +P 200gr 1.1 4.5 10.2
From them you can see that 40 S&W can match 9mm for velocity and 45 ACP for energy (depending on load).
With 40 S&W you get better magazine capacity than 45 ACP, and about 85%-90% of the capacity of 9mm.
Ammunition is less expensive than 45 ACP, and not much more expensive than 9mm.
There is the advantage that 40 S&W is in wide use by LE, so ammo will be widely available.
If I were in combat, I would choose 9mm for the slightly greater magazine capacity, and if I needed something to suppress (sound), I would choose 45 ACP since it is subsonic (without load modification). If money and over penatration were not concerns, I would choose 357 SIG, since it is clearly the fastest, most powerful load. As none of these is the case, I chose 40 S&W for its balance and versatility.
For what its worth, I own pistols in 22lr, 380 ACP, 9mm, 357 SIG, 40 S&W, 10mm, and 45 ACP, but I choose to carry one of the 40 S&W pistols. I carry the 180 load, which has better organ depth penetration than 45 ACP and better permanent wound channel creation than 9mm.
All that being said, I would probably feel comfortable carrying anything 380 ACP and above, and would not want to be shot with anything at all.

Here is the table this is based on. This is for Gold Dot ammo, which I chose, because it passes both the FBI hard surface and IWBA soft surface expansion tests.
Load MZ 50 100
9mm Luger 115gr 1200 1065 976
9mm Luger 124gr 1150 1039 963
9mm Luger 147gr 985 932 887
9mm Luger +P 124gr 1220 1085 996
357 SIG 125gr 1375 1203 1079
40 S&W 155gr 1200 1063 974
40 S&W 165gr 1150 1042 967
40 S&W 180gr 1025 956 902
45 Auto 185gr 1050 955 886
45 Auto 230gr 890 845 805
45 Auto +P 200gr 1080 994 930
Load MZ 50 100
9mm Luger 115gr 368 289 243
9mm Luger 124gr 364 297 225
9mm Luger 147gr 317 284 257
9mm Luger +P 124gr 410 324 273
357 SIG 125gr 525 402 323
40 S&W 155gr 496 389 326
40 S&W 165gr 484 398 342
40 S&W 180gr 420 365 325
45 Auto 185gr 453 375 322
45 Auto 230gr 404 365 331
45 Auto +P 200gr 518 439 384
Load 25 50 100
9mm Luger 115gr 0.8 3.5 8.3
9mm Luger 124gr 0.9 3.9 9
9mm Luger 147gr 1.5 5.5 12
9mm Luger +P 124gr 0.8 3.3 8
357 SIG 125gr 0.4 2.3 5.9
40 S&W 155gr 0.8 3.6 8.4
40 S&W 165gr 0.9 3.9 8.9
40 S&W 180gr 1.3 5 11.2
45 Auto 185gr 1.3 4.9 11.1
45 Auto 230gr 2 7.1 15.3
45 Auto +P 200gr 1.1 4.5 10.2
Comment