If you can find one, a colt mustang pocket lite in 380 or a seecamp in 32. In a larger gun...I still like a SW3913 (again if you can find one)...or a LW 38sp of some kind. I also wear a shirt and tie everyday so it's not really the gun as much as how you carry it. Pocket holsters get old for me quite fast...I've been the most successful with a ppk in an in the pant holster. I clip the holster to my pants in front of my rt hip, underneath my belt and push the whole thing down so that the top of the gun in just below my belt line. Then the natural baggyness of my dress shirt (nothing fitted for this chubster) covers over the top. Just an idea...only thing I'd change is going to a stainless gun...yes...they can rust...but not as easily.
The New Sig P239 is a copy of the colt mustang, so much so I saw an add for Magazines for either and the sig SKU.
When I was looking for a carry gun I ended up with a Sig P230, a much larger gun. But it was something that came out in my hand when I pulled it out.
I think there is a big trade off of stopping power and size of the gun as well as practical shoot ability.
If you are happy having a mouse gun like a Walther TPH, Beretta 22 or 25, and the micro revolvers. Your going to need to practice getting the gun out and in your hand comfortably and able to shoot it. I have a Walther TPH. Tiny little gun and if your hand gets in the way of the slide two things happen
1) you get cut
2) the gun does not eject the spent round. leaving you with an unloaded gun.
All I can tell you is figure out how you want to carry and then shop for the largest gun that will fit that bill.
Having a novelty gun on you is not going to make you safer. i see some of the micro hide out guns as novelty look at how small I can make this.
A meduim framed auto in the 380 or 9mm or a K or J frame sized revolver are going be your chioce for a personal protection gun in the terms of power and useability. While I have talked about carrying my mouse gun it was for a few reasons- 1 I really needed to hide it as I was carrying it Illegally here in CA.
and my worries were mostly 4 legged - Coyote or wild dog while out walking my dog. Having practiced with the little gu every chance I went to the range I was confidant if I needed it for a two legged problem I could answer the problem. I would have felt better with a 380, 357, or 9mm but thought if I did shoot I could justify the 22 for the coyote and dogs out on my walks.
One other thing i found in shooting competions is that the same ammo that is effective out of a 4" or 6' revolver is not as effective out of a 2"
Steel dingers that moved with the 4" gun did not move with the 2" both with similar hits.
An inside the waist band holster and a PDA or Cell Phone holder on the outside hides it well.