The .45 ACP.
How do we know?
It's all over the internet how positively lethal it is, often even if it misses
I hear that the shockwave alone with blow a man's eyes out through his ears
Between the 738 and the 10/22 - it depends on your intended use. Want a target gun - get the 10/22. Want a defensive gun, get the Taurus
I highly recommend the 10/22 - save your $ for a Bersa if you want a good inexpensive .380
ETA: But, understand that handguns are not really all that lethal to begin with, even the legendary and venerable .45 ACP that Mike blasphemed against