No. of Recommendations: 3
Guillotine would probably be the most certain. I don't think that can be botched.
Sure, but that overlooks something.
One of the important things that goes into the method of execution isn't the effect it has on the condemned prisoner. It's the effect it has on the executioners and the public.
It's the old joke about why they sterilize the arm when they're about to do a lethal injection. It's not because they care about what happens to the prisoner. It's because it provides a bit of professionalism/medicalization for what the staff is doing.
Lethal injection gives an impression (whether false or not) of being less barbaric, of being a medical procedure, of being a more quiet and peaceful death. It doesn't outwardly mutilate the body, it doesn't spray blood everywhere, it doesn't involve any overt obvious violent acts.