.... obviously I am armed.

I find it useful for self-defense and the defense of those around the armed individual. Statistically most confrontations are ended with the showing of the firearm. It is unlikely one would need to fire. Distances that armed confrontations take place are often very close to close combat range.

What to get depends on what kind of defense (home, conceal carry) you are looking for and where you live (legality).

I don't want you to tell me where you live so I will assume you live in one of the US states that are lenient with gun ownership (most of them are).

For concealed carry I'd honestly suggest a Glock 19. Glocks are reliable, great "beginner" firearms, easy to maintain, not demanding, and will shoot nearly anything you put in it. The Glock 19 is in 9mm which is a great self-defense round and comes with 15 round magazines.

For home defense I would suggest either a pistol caliber carbine or a shotgun. My knowledge on shotguns is minimal as I actually only own one and bought it with little research. However if you go for pistol caliber carbine you can get a keltec sub2000 in 9mm which takes the Glock 19 magazines. This way you can easily swap magazines between your handgun or carbine. However if you prefer something with better reviews and build I'd go with a Beretta CX4 Storm. With pistol caliber carbines there is little risk they will over penetrate walls. They are small enough to handle close quarters. If you live in a state that allows short barrel rifles and suppressors I would go with a SBR in 300 Blackout rounds and a suppressor. That is currently my main home defense setup.