This sounds like the beginning of a book. A select choice of people get sent to the room and get to choose one button. But they have to give up their memories or morals if they press it. anyways I would choose grey, blue or orange
Just because I'm really into Scarlet Witch right now I would choose Psychic \\\\\\\\\ Warrior! Also, if the mystery pill is just one of the colored pills, why even choose it? Just pick the colored pill you want the most.