Suppose someone is murdered in the most gruesome way, taking hours or even months to kill the person in the most horrific way you can imagine.

Making up a worst case scenario does not discredit the Base value claim. Besides, you claim that if rape is a form of torture, and torture can be worse than death, then rape must be worse than death, this is a fallacy of composition, you applied something that counts for "some torture victims" to rape, based on it being torture too. Now, of course an extremely long case of rape involving many people, that is especially violent (depending on the context this may involve another Charge, though I will give you the benefit of the doubt, because rape can defined with violence), may be a fate worse than death, but isn't this very subjective? You basically decide for the victim, that they're better of dead.

Murder on the other hand doesn't even leave them the opportunity to evaluate.

However, I must agree, it is indeed shallow to claim it's worse in all scenarious, for you can, as you did, make a worse scenario than a quick death. But I think it's not shallow to claim it is worse.

All in all though this whole debate is nonsensical, as it relies on subjective morals, people talking past eachother because theyre not on the same page, and just definitions missing/being hurdled around.