It's just stating my opinion, no sort of gospel. Take it as you will, but keep the 12 year old comments to yourself please.
Despite carrying a .45ACP myself (Ruger P90), I still voted for the ol' 38. You'd be hard pressed to find a larger caliber gun in such a small package that offers all the same benefits. A person can get a nice snub-nosed revolver on the cheap. Ammo is cheap. The gun is accurate in close quarters. Hell....recoil isn't even bad. If you're in a situation where you need more ammo, you're in bad shape. 5-6 shots should be enough to save your ass. If think it isn't, take a class and learn how to shoot more intelligently (note I didn't say accurately).
Yes, I know the issues with 38 and 357 velocity and stopping power. In close counter self defense (that's what I topic the topic as), it's plenty.
Yes, I know you can get tiny little .40 caliber handguns on the cheap (like a KAR or some such). Problem is, these guns aren't that great to shoot. It's hard to practice a lot with a gun that pounds the shit out of your hand every time you fire it. My wife shot the little KAR once, and she won't touch it again. She likes shooting, so to me, that says a lot. Taking that as a generalization, that's a whole gender this type of gun doesn't fit well. Speaking of fit, bigger guns like my P90 are a little too big for me (although I could bludgeon someone to death with it), much less a woman's smaller hands. The 38 is small enough for most anyone to handle easily.
For emergency self defense, a revolver is sweet and simple. No jams, no slide, hell no exposed hammer if that's what you want. It may be considered old school, but the old school saying still holds true....you can always trust a revolver to fire when you pull the trigger. A person that keeps semi-auto in good working condition and uses an ammo the gun likes will nary have a problem, but for general c&c, a revolver is better for the average joe/jane.
All this being said, a .40 caliber semi-auto will most likely be my next gun purchase.