definately Cloud & Tifa, after playing the game, reading the short stories of "Way to a Smile" and watching the movie, it is very apparent that they need each other, they balance and complete each other...
as much as i love Squall & Rinoa, i just can't put their relationship above CxT though it does pull a close second...
the moment Garnet decided to call herself dagger i instantly hated her, why Dagger, that is so lame, and to top it all off she's a furry, so not even on the radar there...
as for Yuna & Tidus i loved them as a couple but sadly Tidus isn't too bright and totaly missed the part where she was planning to die untill it was almost too late, they don't necessarily need each other, but their love is strong enough that Yuna keeps looking for him after his dissapearance...

Cloud & Aerith didn't even have a chance from go, since it's Zack & Aerith and always has been... i love this couple as much as CxT...