For me it's not that black and white but I'll try
1.One of your enemies - Slide
2.Multiple of your enemies - Slide
3.A random innocent (you do not recognize) - Slide
4.A large group of random innocents - Slide
5.A person who you recognize (met before, and don't dislike) - Slide
6.A large crowd people you recognize - Slide
7.A friend - first hard choice, slide unless he/she has saved my life before
8.A large group of your friends - slide (same as above)
9.A close friend, loved one, or family member - that really depends on who it is. If it's siblings, slide, parents knife.
10.A large amount of your close friends, loved ones, or family members - same as above, if there are ones that matter to me or that I owe my life to (like parents) knife, otherwise slide.
11.A large group of all the above combined totaling to an uncountable number but all the recognizable faces can be seen clearly. (excludes enemies) - If I don't recognize anyone I truly care about among them, slide, otherwise knife.