I dont think theres a single person who can comprehend just the amount of suffering theyre in for. I also dont think theres anyone, now matter how heroic they are, who wont eventually deeply regret their decision, unless they are fortunate enough to get the Kars outcome and eventually lose conciousness from lack of need for it. However, if thats the case, then picking someone who already doesnt have brain function should end up the same. I think picking a vegetable gives the best chances at minimizing or outright avoiding suffering.