I carried both a 6-inch and a 4-inch .357 duty gun in the mid-70's. During that time it became well known that the Remington 125-grain SJHP (semi-jacketed hollow point) was one of the best performers at stopping someone. Several methods of testing & evaluation rated it "excellent".
Shortly thereafter (late 70's/early 80's) agencies started shifting to semi-autos. One agency permitted officers to use either 9mm or .45 ACP. The .45 was favored about 2:1 initially. At this time, 9mm JHP ammo did not perform as well as today's JHP ammo. Some spectacular failures-to-stop occurred (one in which a perp was hit 13 times by three officers with 3 different brands & types of ammo - and survived to walk into court a year later. Four of the hits were "COM"). The selection of the .45 jumped to almost a 3.8:1 favorite.
The downside of the .45 auto is that it can often fail to penetrate barriers as well as the more potent .357 Magnum. In terms of its ability to cause a perpetrator to go down, the .45 ACP has a very good (but not quite excellent) record.
Since that time, however, the design, construction and execution in the making of JHP ammo has improved at least an order of magnitude. In the 70's, reliable expansion was if a round expanded more than 68% of the time. Many popular .38 and .357 rounds failed to expand more than 10% (didn't reach .40 caliber) and most deformed instead of expanding. Things were dismal in the .45 ACP realm too. JHP's expanded only about 45% of the time and usually failed to exceed a 10% expansion.
Today's ammo is much more reliable at even lower speeds than ever before. Using modern .357 or .45 ammo is a quantum leap over what was available 30 years ago (yet, lots of thugs ended up on morgue slabs regardless of the bullet design).
My preference for personal defense in popular calibers is the .45 ACP first. While it may not expand, it will certainly always make a .45 caliber hole. The .357 Magnum makes a very good alternate choice if one can shoot it well despite the intense noise, concussion wave, muzzle flash and heavy recoil.
In standard configurations, the .45 Auto holds 1-2 rounds more than the .357 six-gun. Not a serious advantage, but some. Plus the .45 is typically faster to reload. Balancing power, shootability, reloading, reliability, etc. there is no "clear winner" between the two. I know at least one pistolero who is a very good shot with his .45 Auto, but he his scary-accurate with a .357 Magnum at 75 yards.
The 2.5" snubby .357 does give up some velocity and energy. But on the whole, it is still a step up of from .38 Special. The rule of thumb seems to be that the .357 loses about 25% of its rated 4-inch barrel velocity when fired fom a 2-inch barrel. There's no reason to discount the typical 2.5" snubby or even the 5-shot S&W J-frame as "inadequate".