I would agree, somewhat.
The 357Sig is a .40 caliber casing--necked down, of course. uses .355" bullets.
The others are basically 38's/9MM's, almost interchangable.. use either.355" or .358" bullets
One can shoot .357 bullets in some of them but without the full effect..either way, same caliber
The loadings of each are dependent on a number of factors..no effect on caliber of bullet
The casings and rims are different.. no effect on caliber of bullet
The 9x23 casings I use are winchester and are high pressure casings.. no effect on caliber of bullet
You are correct of course and incorrect only somewhat.. with cases, loads, rim styles not having any effect on the actual bullet calibr, I'd say that I was NOT somewhat incorrect in my statements. If so, please point it out and accept my humbled apologies.
Regardless, with the .45 being the exception, the others are all the same caliber. Remember, caliber is the bullet diameter. The casings used, the cartrdige used, the type of rim or the loadings are still not the factor deciding the actual caliber.
Also realized I never answered the initial question. For my guns I'd potentially carry, I'd have something chamered in either 9mm or .357 magnum. For simply range plinking, I routinely use handgns chambered in .22lr, .32 H&R magnum, 9mm, .357 and occasionally .45 Colt. Hunting, well, narrowed choices here. Either, .41 magnum, .44 magnum or .45 Colt.
I kinda like the smaller calibers and having just bought a multi caliber handgun, I'll be likely venturing into the realm of .25 caliber soon as well as adding the .380 cartridge to some range sessions.