SPOILER ALERT: Just in case it wasn't obvious, the remainder of this thread will be littered with spoilers of all kinds.
SPOILERS EVERYWHERE AFTER THIS POINT
Noctis and Iris. Definitely. She's adorable. If Luna were dead and Noctis alive, I think she'd be the correct one for him to end up with. Buuuuut Noctis in game is definitely 100% Luna so I can't do much about that.
Prompto & Coctura because I just can't see him ending up with Cindy or Lady A.