In terms of 'which is better at killing a human', I don't think you will find a measurable difference between a .45 acp & .357. The 45 makes a somewhat larger diameter hole, although there is dispute about how much larger. The 357 penetrates deeper, but humans are normally shot in a location that doesn't require 20" of penetration. Remember, ballistic charts and ft-lbs don't kill. Wounds that hit something vital do.

What is enough? I prefer to carry my 7-shot 686 3", but that is because I can shoot it better than I can my 60LS. Arizona doesn't have strict laws on carry - quite the contrary - so I don't have to worry about deep concealment. I tend to think of 'discrete carry' rather than concealed. Also, most of my carry is done for 1-2 hours, with a lot of it in a car. Other states and other needs would drive me to use the 60LS...with 38+p since I find the 60LS with small grips a pain to shoot well with full power 357 loads. A pain to shoot, period, unless I go to 38+p. With modern ammo, a 38+p will give 12-14" of penetration with OK expansion. 45 acp would give about the same amount of penetration with a slightly bigger hole.

In some environments, more rounds may be good. If so, the semi-automatics are great. I just hate semi-autos, so I don't practice with them and so I don't carry them.

The only time I pulled a gun was 30 years ago. I was returning from a hike, and 8 guys started to fan out around me at my car. I had a 6 shot 22 with me, and they decided that was enough...and no one was shot. But I had fired a lot of rounds with that 22, and was confident the closest attacker would take a shot in the face - and maybe that confidence showed. And no one wanted to try a shot in the face, even with a 22...

My perspective? Find a gun that fits you well, that is instinctive to use, and that you love to shoot. Find a rig that allows you to carry it, and do so. If I was a bad guy, a fellow who knew, loved, and practiced with a 5 shot 38 would scare me far more than someone with ANY gun they had to think about how to use.

Oh...and most gunfights involve panic. The more one practices, and the more scenarios one has thought out in advance, the less one will panic. I plan on my gunfights - which hopefully will never happen - involving a string of one shots. The other guy gets to shoot back, so I figure shoot & move. When ready, shoot & move again. If we're too close to shoot & move, shove the barrel in his belly pointed up and shoot until empty.