LAK, I have to disagree a bit.
There are actual studies out there that give 'stopping rates' for various service calibers. The one shot stop study, for example. Which basically concluded that bigger & faster was better - and hollow points gave smaller, but high velocity, bullets a larger advantage than they gave big & slow ones.
A handgun isn't going to knock anybody down who wasn't already going down by momentum transfer, no. And knockdown power isn't even really a reality even with the near mythical .50BMG.
Madjohn, there's been enough studies and arguments here and elsewhere that the real advice is pretty simple. Go for the most reliable, accurate and comfortable for you firearm and ammo combination, preferably in a 'major power' - the .40, .45, and higher velocity 9mm. A moderate hollow point, especially for the relatively high velocity 9mm.
As for the murder comment - a lawyer might try this in a court room. Any competent defense lawyer will promptly point out that hollow points today are pretty much standard issue with police departments across the world, is he trying to say the police load up to commit murder?
My dad even came across a study once that suggested FMJ has a higher fatality rate - because people shooting it end up shooting the BG another time or two to stop him, and the resulting damage from an extra couple rounds tends to kill the BGs vsfewer hollowpoints that leave fewer, if a little bigger, holes for the BG to bleed out of before the docs patch him up.