Looking at death purely from the how-does-it-feel-like point of view overlooks one big dissimilarity. In our law and I would guess in your too a planned killing is treated very different from a death as an unplanned consequence of mistreatment. Both are wrong and are deservedly punished but the sentences differ a lot.

Just for a moment consider the USA would announce that from now on they will decapitate a Guantanamo prisoner for each US soldier killed in Iraq. Would you really argue seriously that there is not much difference since the two death by mistreatment must have felt at least as bad as the decapitations? You wouldn't. And therefore you shouldn't downplay the beheadings by wrong comparisons.

Just in case you are interested, If that was the only choice left I'd prefer being beheaded to being beaten to death, but as I have argued that should not matter here.

Wolfgang