In this realm, I'm a little confused whether to go 9 millimeter or .40. I think the
.40 is the one for the ultimate stopping power and has been recommended to me by any police officers I've spoken to, but on a smaller gun it's going to be much harder to practice with. The 9 millimeter can have very good stopping power, is cheaper to shoot, and the recoil is much more manageable. And then you look at ALL the choices, Ruger LC9, Kahrs, Glocks, Springfields...I could name many more, but you see the point.
Like I have stated before 95+% of the replies are opinions.
In my opinion there is NO ULTIMATE caliber in a handgun for stopping power. How many people have been killed by the meek 22lr round????
If you do your job with regards to hitting COM the center fire round will do its job and stop the threat. Again remember its 95+% opinions