Thats sick. Your sick. How dare you bring, incest? into this.
Actually... If ya really wanna think about it, Namine is technically made from bits of Sora so, what do ya wanna say about Chain of Memory, eh?
Anyway, on topic, I kinda like Roxas and Xion more but, not for the stuff you suggested. I find them... originally innocent and then wrongfully used, kinda. Their story was like taking toddlers and then handing them a gun saying, 'okay, you gotta kill these things and these people and then we'll like you' only to plan on having them rip eachother apart in the end.
Yeesh....