Shot placement, shot placement, shot placement!
If you are a very experienced and skilled, double action shooter, it doesn't matter . . . for you'll be shooting double action anyway in a defensive mode.
If you are NOT a good double-action only shooter you might want one of the models that has a hammer to help you master the sights and the grip on any of the "wee-beasties."
However, on any of the ones you chose, your goal should be to become a proficient double action only shooter with a j-frame.
My druthers . . .
1. A nickle-plated steel or stainless hammer type (Chief's Special or Bodyguard), carried in an IWB holster, plus
2. An Airweight or Airlite hammerless Centenial type as a BUG (Back Up Gun).
The slightly heavier steel j-frames with hammers can shoot amazingly well, cocked and shot single action, and are great if you need to take a longer shot . . . or want to have some REAL satisfying fun at the range.
Here's what my nickleplated Model 36 does at 10 yards, single action, standing and unsupported. Frankly, I didn't expect this out of a J frame snubbie:
Also, the heavier gun that can be cocked will really help you get used to shooting your lightweight j-frames more accurately . . . and with less grief on your hand.
.38 special vs. .357? Either will get the job done with good shot placement. Neither will if you don't put the bullet(s) where they ALL need to go. Any deer hunter knows that a single heart shot on a deer does not always bring that deer right down. Two legged predators are the same . . . and accurate follow-up shots made before the once-shot BG can pop a cap or two into you may save your life.
NO handgun bullet and/or caliber is exactly what I'd call a "powerful" round! Plan on needing multiple shots in any defensive situation and hope to be surprised if this is NOT the case, rather than visa-versa!
1. Sure, a hot .357 will be more effective IF you put the first shot on the mark AND need no others. However, the massive recoil of a hot .357 round in a J-frame will truly slow down, and/or affect, your ability to get off additional accurate shots in a timely manner.
2. However, the .38spl. rounds will be easier to shoot and MUCH EASIER to make fast, accurate multiple shots.
The fight ain't over until the bad guy decides to give up . . . and I'd rather have .38 spl. in my J-frames due to better controlability and accuracy on shots #2-5. If it ain't over by then I'm either hightailing it outta there . . . or doing a "NY reload" (drawing the BUG!)
Food for thought,
T.