My most concealable gun is my Sig P238. It's a 6+1 .380 that functions beautifully. It's small enough to carry in a pocket and not be noticable, yet is a fairly soft shooter that can be shot very quickly and very accurately. Since I tend to carry it in the pocket, it gets a lot of lint on it, despite being in a holster. Once in a while, I'll hold off on cleaning and will shoot it in its most lint covered state. There are times when you cannot even see the firing pin where the hammer hits it. The first shot makes every bit of lint disappear instantly. It's never even hiccuped when shot like that. I have complete confidence in the little gun and think it's one of the best choices for a deep concealment gun.
Definitely the easiest little gun to carry is the NAA Mini 5 shot 22 Magnum. Reasonable in price high in quality. The best gun you have is the gun you have when you need one.