My choice is a 240 grain bullet of some type (depending upon specific purpose) for deer/men and smaller. A 300-330 grain hard cast bullet is used for everything bigger. Velocities may be varied to suit individual purpose as well. Usually plinking fodder is a 240 grain cast lead to a little less than 1000 fps, doubles for head shooting small game as well. Never had a rabbit walk away yet
Keeping it fairly simple!
P.S. It is not normally my choice for defense against two-legged predators.