How does one define "beat" in this context? On another thread the other day someone posted a story about a police officer who shot a perp 14 times with his .45 ACP before the perp went down and he was still breathing in the emergency room. A lawyer buddy of mine tells the story of his former client, a drug dealer (yes, yes, they hire lawyers in case you didn't know) who shot another drug dealer 6 times and the guy got up and came after him.
So there is no "mo bigguh mo bettuh" round. You shoot what you practice with, presuming you're a real gun person and not a newbie with a new gun and maybe it's carried and maybe it's not. If you don't think you can protect yourself and others with a 9mm then by all means carry a larger caliber but don't denigrate the 9mm, a round that likely accounts for as many or more deaths worldwide than any pistol caliber. Every military in the world has been using it for 100 years EXCEPT ours and then they switched, too.
You do a Moazambique drill on a bad guy in any caliber his day is done. Shot placement is the key, not caliber.
Anecdotal stories abound. .22s have killed so many people the number is staggering. Do you think the dozens and dozens of people being killed across America every day, whether innocents or actual criminals themselves, shot by gangs or violent offenders newly released from jails, were all killed by .45 ACP rounds or .357 Magnums or 10mms? This is a never ending debate, I don't have a picture of a dead horse or I'd insert one here, but claiming to know the BEST caliber is just silly.