well, for ccw, choose the handgun bullet performance you want, and work backwards...to the platform that suits your lifestyle. i think a lot of folks wind up back with the 9mm Parabellum and 45ACP and whatever platform meets their needs.

https://www.luckygunner.com/labs/self-defense-ammo-ballistic-tests/


You can make a similar argument with hunting or target bullets... choose the desired effect and work backwards to the cartridge and platform.