I have chosen to carry a Smith and Wesson Bodyguard .380. I get a lot of grief from some of the guys for carrying such a small round. But like the lady's say “it's not the size that matters it's how you use it”, and I use it every day.
The Bodyguard .380 is the only gun I have that I can put it in my pocket and completely forget about it. I don't like having a holster rubbing on my hip, or getting caught on seat belts all the time. It also has a nice safety and Lazer that increases the guns usefulness in my opinion.
Now as far as take down power the .380 round has came a long way. I use lehigh defense xtreme and like it alot.
This round has a new design that makes the bullet spin inside of the target creating a bigger wound channel. Below is a comparison between the lehigh defense round and and normal PMI ball round. Notice the consistency in the chanal with the Lehigh, and how it stays open longer.
Lehigh Defense
PMI ball round
In the end it doesn't matter what size round you carry. What really matter is having it when you need it. So carry what is most comfortable to you.