Perhaps odd wasn't the best term, but it was easy for me to spell.
I personally have never seen the two options compared. Well except for a sign in a gun shop saying that 357 Sig wouldn't fit in a revolver.
all pre coffee, but more expanding my thoughts
.357 Mag in a revolver is one of my favorite handgun rounds. I have six(?) revolvers in it and am trying to find an affordable pre safety lever gun or a 77/357, I like it that much. So many varieties in magnum loads and you can also take it down a notch or two with 38+P or 38. 357Mag doesn't make an awesome defense round unless you've trained with it bit and learned to control the recoil. .38+P in a revolver would be easier.
.357Sig. Another capable round, but few variations to it. Kind of a solution looking for a problem so to speak. It will be easier to shoot than the revolver.
Of the two, I would still stick with the easier to shoot and higher capacity semi auto cartridge.
9x19 has come a long way since it was introduced in the early 1900s and you already carry a 9mm. A good article here which has 357 sig vs 9x19 gel tests. Also goes into the why of 357Sig, hence the strikethrough above.
.357 Sig: What's the Point of this Cartridge?
At the end of the day though first rule of a gunfight is to??? besides trying to avoid it, it is to bring a gun. Preferably something you can shoot several times well in a stressful situation.