If you were in this hypothetical scenario, would you rather make out with your mum or kill a friend? What is your reasoning?

This was brought up by a certain Jelly who shall remain nameless as we watched Back to the Future.

Marty goes back in time and in order to correct the mistakes he made and guarantee his existence he creates an elaborate scheme to help his future father get with his future mother. The scheme involves Marty making out with his own mother so his father can save her and be the hero. But, could he not also have just killed Doc Brown, therefore guaranteeing the time machine never be built?

So the question is, make out with your mom or kill a friend to save yourself? What is the reasoning behind your choice? Was it a hard decision to make?