When I was doing the basic concealed weapons course for civilians I put about 20 handguns on the table for students to handle and to find a proper fit. My criteria for a carry gun has always been that it fits your hand, you can operate it, it is centerfire, it is reliable, and most importantly, you can hit the target with it.
A number of students showed up with guns chosen for them by someone else who may have been well meaning but not knowledgeable. Gun store clerks are notorious for pushing bad choices. Example: A 70 year-old woman with an Airweight revolver will usually want to get rid of it after firing the first shot and experiencing the recoil; a person who cannot operate the action has a useless piece of metal. The ergonomics of the gun need to fit the shooter. Then there are trigger weights, trigger finger length and strength, physical disabilities, and the list goes on. A lot of thought and trial goes into getting the right fit. And a person who cannot shoot the gun comfortably is not going to practice with it. Different strokes for different folks.