Gun Control & RKBA

There are far too many variables. For example what works in rural Alaska isn't going to work during a Florida summer.

A person needs to pick a gun that is reliable, accurate, fits their hand and that they shoot well.
Are they in a job that involves higher then normal risk (cab driver, pizza delivery, handling bank deposits, etc)?
Environment is also an issue, it is a lot harder to hide a larger gun in hot, humid weather.

Revolver vs semi-auto:
Revolver: Based on 20+ years of competitive shooting, a revolver is more reliable then a semi-auto. HOWEVER when a revolver jams, it will almost always require tools and several minutes, at a MINIMUM, to clear the jam. I also find that most people find a revolver harder to shoot well. To shoot a revolver well require more time and training then a semi auto to reach an equivalent level of skill.

Semi-auto: Slightly more prone to jams, but most semi-auto jams can be resolved in seconds and without tools. Most people will shoot a semi-auto better then a revolver given an equivalent level of training and practice.

My personal preference for a small 9mm is the Kahr PM9. It is light, very accurate, the trigger is very good and with factory ammo it has been 100% reliable.

For a full sized gun, take along look at the Steyr M9 & M40, it's kind of an improved Glock: a better trigger, fits even small hands very well, accurate, reliable and has the lightest recoil of any 9mm I have ever fired.