I occasionally check into various forums dealing with 1911 style handguns, if for no other reason than to keep up with the latest poop being jawed about. One of the classics debates that people (especially those new to these forums) is oil versus grease for maintaining your pistol. There are partisans for each, with a known set of reasons for each choice, and then there is the great majority who use whichever product is most effective in their particular environment. Similarly, the other classic debate is the fabled 9 mm versus .45 ACP. This debate can be extended to include .38 Spl, .357 Magnum, and .40 S&W or 10 mm. Bearing Arms has the usual debate ender when these arguments get started at 9mm vs. .40 vs. .45 which is better for self defense?
I get asked every now and then by people who are new to shooting: "What gun should I get?" often followed by "Which bullet is best for self defense?" I tell them the same things. If you are new to guns, take a basic course to learn how to shoot safely. Rent some guns you are thinking about and try them with a box of ammunition. See which ones you shoot the best. It is better to carry a .32 ACP that you can shoot well, than a .45 ACP that you can not.