While funny as all hell - nearly every single guy I know who's opinion is highly valued chooses 9mm Glock as their fighting gun/pistol. This includes those with significant experience in direct action, including both Tier 1 units, and who currently provide outsourced training and consulting to same.
Once you are up to the major defensive pistol calibers and quality expanding ammunition - the game is quickly and efficiently putting multiple hits on vitals until the threat is eliminated (i.e. lots of holes to drain and disrupt blood flow). 9mm is the game winner here and Glock is a very efficient and ubiquitous platform with mechanical accuracy good enough to get any job done providing the user does their's.
Now reality is that all pistol calibers suck - unless one is on a TV or film set living in fantasyland - and rifle owns all day. Covert work and most daily lives lend themselves more to pistol carry. My odds of being in a gunfight are fairly low where I live. If they were high, I'd move.