I've held myself away from here for TOO long >:D
Okay, I'm going with Sora and Kairi for several reasons.
AND HERE IS MAH EVIDENCE:
1. In the beginning of Kingdom Hearts 1, the Paoupou fruit is talked about in a romantic way, saying it will wrap up two people's destinies forever if they share one. Sora acts on this by drawing a mural of himself giving Kairi a Paoupou fruit.
2.During the credits of the same game, Kairi is seen discovering this mural and adds in herself giving Sora a Paoupou fruit.
3. During the events of Kingdom Hearts 1, Kairi gives Sora a Wayfinder, which is symbolic of a relationship between the giver and receiver (seen manifested as Dimensional links were the two draw on each others power to fight in Birth by Sleep). Sora uses the Wayfinder as a Keychain, symbolizing that he is always thinking of Kairi when he is in battle.
4. Towards the end of Kingdom Hearts 1, Sora goes as far as sacrificing himself and injuring his best friend for the sake of saving Kairi's heart. After this, Sora is trapped in the darkness, but seeks out his light when he is stuck there. This light is Kairi, who notices something different about the heartless following her. She hugs the heartless and it is returned to its true form (Sora). Sora and Kairi's relationship is so strong, that it was able to pull Sora out of the darkness.
5. During the end credits of Kingdom Hearts: Chain of Memories, Naminé shows Sora all of his old friends and restores his memories of them. Sora sees everyone almost simultaneously, but does not react in happiness until he sees Kairi, completely ignoring Riku.
(Pssst, I might change this some more and add some more reasons when I finally get a chance to play KH2)
Although there may be some times were Riku has shown attraction to Sora, he ignores this. Anytime Sora is seen showing what MIGHT be attraction to Riku, it is usually him acting to save or help his best friend.
My username's Sora. I love Pokemon, Kingdom Hearts, and seeing this community thrive.