Lately I'm split pretty evenly between 357 SIG (tiny G33 for long drives to the office) and .45 ACP (G30 which gets more comfortable as I lose weight). I may go to 9mm more often, though, because I'm really getting to love my CZs.
And, it's always good to have options (for guns and ammo), 357 SIG was generally available during the ammo panics, .40 is getting cheaper as it loses favor with LE agencies. .38 and .357 for SHTF is easy to reload to a wide variety of specs, shoots from reliable revolvers and lever guns. .44Mag and 10mm for when every shot needs to count. And 9mm is the absolute king for normal availability, variety, price, price/performance, capacity, etc.