Why Marry? Because Gendry will stand by those he loves, as evidenced by all of the risks he's taken for Arya's sake. He will likely be a dedicated family man and, as a talented blacksmith, a reliable provider.
Why F***? Because all that blacksmithing has turned Gendry into a muscular young man who is skilled with his hands. And who wouldn't want to gaze longingly into those blue eyes all night?
Why Kill? Because as Robert's bastard son, he brings with him a lot of drama and a healthy dose of danger. Killing him would be for the good of the realm.
Why Marry? Because he is a gifted warrior and has shown how devoted and generous a husband he can be.
Why F***? Because he has proven himself to be a very powerful yet tender lover.
Why Kill? Because the Dothraki are prone to violent fighting and spend their free time pillaging cities. Or because you're a maegi.
Why Marry? Because he is, quite literally, a knight in shining armor; beautiful and skilled, Loras is beloved by many. Plus, he might be up for an "open" relationship, if that's your thing.
Why F***? Because every girl in the Seven Kingdoms wants a piece, and how great would it be to be the one who actually gets to bed him?!
Why Kill? Because Loras is a little too full of himself, and the toll his heart has taken due to Renly's death could make him a bit too unpredictable.
Cedar: Marry Loras, F*** Gendry, Kill Khal Drogo
Erin: Marry Gendry, F*** Khal Drogo, Kill Loras
Jamie: Marry Khal Drogo, F*** Gendry, Kill Loras