The primary issue with life incarceration or the death penalty is that it’s carried out by the monopolistic gang called the state. There’s no right answer in our system. 
The third way is to abolish the state and let the free market justice system work ( ie Bob Murphy, Bruce Benson and David Friedman) The closer the state can approximate these systems by getting out of the way (like allowing discrimination against criminals) it would be better than what we have.