Wow, it's been a while since I've seen one of these. The "better half" makes it sound like we should pick on who's the good one, though, in terms of who's the purest. Nonetheless, I prefer Roxas completely. Sora might have that hidden Darkness within that he keeps away with a smile, but he's still sort of bland to me. Roxas (other than Riku), was one of the characters who actually had very negative traits to them and earned some of the consequences that came about: temperamental, selfish, short-sighted, a bit of a jerkass, attitude problem, etc. I appreciate the hcraacter for that, since we've had too many cookie-cutter people. He has a lot of quirks, and he manages to balance it with a little cheerfulness, and concern for his friends. He isn't a stranger to laughter.
So, yeah, Roxas.