Statistically fighters are way more likely to be finished after being dropped by a body shot then a head shot.
As far as the most painful strikes go, the last time I cried was after basketball practice in grade 7. My buddy blindsided me with a north to south elbow straight to the spine. That shit fucking hurts.
"If a man with no arms and a man with no legs started learning karate, the same light bulb would appear over every head in Japan. Thatís right: Glue them together and see if it can kill a panda."