Personal protection. First time gun owners looking for advise on what to get by and large fit into this category. Children are not really applicable as the parent is already a gun owner if the kid grows up shooting. And most prospective new owners are not looking to go straight into big game hunting or 3-gun matches. That narrow it down enough?
For a first gun, that was expected to be used for defensive purposes, I used to suggest a .357 revolver for its simple manual of arms - pull trigger. There was a time when .357 was the most effective round, based on police experience. So, .38 for practice and .357 for carry in a reliable platform made a lot of sense.
But ammo has changed, and there is no statistical advantage to .357 with modern defensive ammo. The revolver is heavier, more expensive to purchase, and has lower capacity than a good 9mm.
Given the reliability of a good 9mm like the Glock 19, and the higher ammo capacity, better ergonomics, lower ammo cost and greater ease of follow up shots, along with more numerous accessories like holsters and sights, and I’m going to suggest the Glock 19.
If I had to own just one gun, I would be hard pressed to choose, but the G19 tops the list.
Small enough to be concealed but large enough to give a good grip for most hands. Good ergonomics. 15+1 ammo capacity. Total reliability. Moderate cost.
I taught my kids to shoot handgun with a Glock 19*. My youngest was 13 when she learned. On her first range day, she was putting most of the rounds in the X ring at seven yards. Far better than the average shooter I see at the range.
If a 13 year old, female, new shooter can master a Glock 19, with proper training, anyone can.
*She got great training. This is a critical point. Her first day learning to shoot was on the US Navy’s shooting simulator with a small arms instructor, not me. The weapons were real guns, modified with a nitrogen actuator for the cycling of the action, and a laser in the barrel to score hits when the firing pin hit the sensor.
She learned M-4 and M-9 with simulated firearms, and got the fundamentals of shooting down in a low noise, no recoil, supervised, and precision scored environment. It was the best way to learn. When she transitioned from the M-9 to the G-19, she already had the fundamentals down.