Efficient, quick and definitive, plus they horrify liberals, which is fun.
No need to be concerned about "quick." And a noose can be repeatedly used. With no "carbon footprint" from a firing a bullet, in addition to removing the "carbon footprint" of a murderer, that makes the execution "Green" so liberals, other than the murderer, can't complain.
I’m fond of the old western style hanging complete with hymn singing before the trap door is sprung. It is not only a nice way to put the perps in the best frame of mind to meet their maker, but it would horrify liberals even more.