If I was forced to choose then definitely the former; I don't think I even could have sex with my mother's body, that'd be way too disturbing. Also it's easier to pretend it's actually your waifu that way.
There is a virus that's going to kill the entire human race if nothing is done to stop it. You have the means to distribute two vaccines: one has a 60% chance of saving everyone (and a 40% chance of being completely ineffective), while the other only works on 60% of the population (meaning 60% will be saved, while the other 40% will die for sure). Which vaccine do you go with?