the right answer is any gun you can handle, fits your hand and you shot well. Doesn't matter if it's a revolver or a semi. What matters is you shoot it well. After that, its up to you.

Personally i love XD pistols. I have a 9mm service. That is not an easy gun to carry concealled however. I now have a .380 thunder which is my carry. Load it with good bullets and i am protected. I think alot of people get hung up on semi auto's with big bullets when if they needed it, they couldn't hit a target in time. I laugh when people say the 9mm will not stop a human being who is attacking you. Just not true. If you are good with your firearm and feel comfortable any gun is better than no gun in a life/death situation. Also don't rule out a revolver. They are easy to operate, safe and easy to carry.