Caliber - .44. Cartridge .44 Special. BUT, though the OP instructed that platform (use, etc) was not to be considered, it almost has to be. While, cartridge-wise the .44 Sp will do everything I ask--or can conceive of asking--a .357 to do, the latter would be my choice if a carry handgun - 1-2 more in the chamber, generally lighter gun, off-the-shelf ammo availability, etc. (Hard times, emergency/Post Sandy/Katrina, etc).
Back to the OP,...when following instructions that such "operational" characteristicss are not under discussion, just strictly caliber (or cartridge which is probably what he meant) chracteristics, I'm back to .44/.44 Sp. - hands down. Same "effective effectiveness" as the .357, less sturm-und- drang, chance you might get your hearing back if shot indoors or even caught "having" to shoot outdoors without haring protection. Decent SD-thru-game hunting energy. Larger hole. Better range (and loading variety) than the otherwise very similar .45 ACP. What's not to like?--again just talking cartridge, not gun. Strictly caliber discussion (vs gun) opens this up to .44 Mag. As a previous poster said, load it up or down, most versatile cartridge out there, especially when availability is taken into account. I'll grant the .45 (Colt) boys will have a point arguing at least parity if you reload.
Last edited by gak; November 1, 2012 at 12:37 PM.