Are you speaking in terms of general purpose or just for SD purposes. For SD, it it is hard to beat either one, except of the limitations of number of rounds in a revo chambered in .357. I would prefer an auto pistol for SD, so it would have to be a .45 acp for that purpose. Have 4 of the .45 auto pistols I use more than anything else in an auto. As a general purpse firearm, I would use a .357. Mostly cause of the .38 spls. which I shoot the most of for plinking and such. Hate losing brass like with the auto pistols cause I reload for both. And it is still right up there for SD in .357 if ya have nothing else. Other things to consider about .357s is muzzle flash in dark areas and recoil recovery time with hot loads.
If I had to make choice of one or the other, it would be the .45 in an auto pistol. It does everying the other round does and for serious work and ya have more capacity in most cases and faster reloads.
They have different purposess in my opinion. I once leaned up a 2x4 against a old barn wall and fired a .357 at it and it went through it and then the wall and into the ground. The .45 went in and stopped but the 2x4 was flung back at me showing that it absorbed all of its energy because it did not go through. So the .357 if you are shooting at something that needs a lot of penetration ( a large muscular man with heavy clothing,leather jacket). But if it is not something out of the ordinary the .45 delivers a lot of shock to the body. I once read an account given by a sheriff chasing a bank robber on horseback that got shot in the leg by a .45 auto ( back in the 20's ) his comment was getting shot by a .45 takes all the want to out of you. So I think the .45 auto is best all around gun.
I'm a .45 fan and love the round. But my experience growing up was always told 357mag was very good ... Dad would never own a semi-auto he was old school and believed revolvers were the best. But I disagreed for many many years but as now I'm older and shot a lot out at the farm & i tend to always go away from the 357 for awhile and use others but in the end I keep making a circle and re loving the 357 every time .. I guess I'm crazy lol