I’m reading a book right now set in space. A character in the book has been found guilty, beyond a shadow of a doubt, and the sentence carries the death penalty. You, John Q Doper, reading this thread ARE that person. There is no appeal. There is no debate. You WILL die. Your only choice is in how you will die. You can be hung by the neck until dead. You can be given a lethal injection that will kill you in minutes. You can be electrocuted. You can be spaced. Hell, the captain will allow you to be put into an escape pod and fired into the sun or left in that same escape pod until you run out of air and suffocate. The choice is yours and may the gods have mercy on your soul (or whatever).
And, were firing squad permitted, I’d ask, please, that they aim for my head, not my heart. That way, my brain will be destroyed faster than the nerve impulses moving within that brain. “Dead before you know it.”
(But I’m told that the shock-wave of blood pressure from the heart up to the brain knocks the subject out instantly anyway, so even with a heart-shot, there’s no pain.)
Seriously, firing squad. No blindfold. The rumor is that the blindfold is for the benefit of the squad, so I’d want to creep them out with my death stare.
There’s also the Schrödinger box from Endymion. (IIRC) Poisonous gas is released as a result of random decay; you could be killed in mere minutes or it could go off decades later long after you died of old age, therefore the state isn’t technically culpable. The hitch is that it’s basically solitary confinement until then.
Having been slain quite a few times, I can recommend anything that causes you to bleed out in short order. Yes, the injury will hurt, but it’s not so bad, really. Not nearly as unpleasant as suffocation or starvation or a sword to the gut. I don’t recommend anything that destroys the brain outright; hypoxia gives you a, ah, “smoother shutdown”.
If it’s done right, by someone that knows what they’re doing, it’s over in a couple of seconds. Old timey hangmen used to take pride in dispatching the condemned within less than a minute of them walking onto the scaffold. If it’s done wrong though, it can be a horrible slow death by choking.
So yeah - given a decent, experienced hangman, then hanging. If not, guillotine maybe?
Or if I’m allowed total creativity, then there’s always something like this:
Edward de Bono is my Deus Ex Machina.