I was looking for a coyote and deer rifle a couple of summers back. I wanted something that had some legs on it, but that wouldn't beat me up too much to shoot it. I had a long list of cartridges that were acceptable for what I was thinking about, but I ended up buying a .243 because it met all the other things I was thinking about, and I noticed that of all the calibers I was thinking about, it was the one that passes the WalMart test. I was at Wally's last night. They were cleaned out of .22 rimfire, .223, .38, .308, etc, but - in .243, they had a stack of Federal Fusion, a few boxes of Remington Core Lokt, and a couple of Federal blue box softpoints.
None of the other calibers I was considering were on the shelf. Most of them, other than the .25-06, aren't even carried by Wally's.
My rifle's only seen one box of factory ammo, but it's nice knowing that I can run over there and grab a couple of boxes if I need to.
Other than that, I've got .22 rifles and pistols, a .50 muzzleloader, a K31 (that I hardly ever shoot, but it's cool and I got it on a ridiculous sale - just got a bayonet for it, too), a 5.56 AR, a 9mm, and several S&W .38 and .357 revolvers. My shotgun is a 20g.
I only have one gun I never, ever shoot: a Hollis revolver from the 1870s that I got in Kabul. It's some kind of .45 caliber cartridge.
IOW, the guns I use are in normal, common calibers. Unless I actually build the 6.8 upper for my AR I'm thinking about, that's probably how it's going to stay.