Don't get me wrong, I love Sakura and Syaoran...they still make me 'squee' like a little fangirl whenever something cute happens between them...but...we've seen it before. Sure, they're so adorable and so confused with love, but we've seen their relationship in CCS. So, for TRC I'll have to say I prefer KuroFai: it's something new, and there's a serious dynamic about it what with the yin-yang personalities. They clash, but mesh at the same time, and that's REALLY fun to watch.
*votes KuroFai*