I'm with Moonlady on this. I didnt really think any of them would be good with Squall.

Rinoa - She's such a child, and like WrightRaven said, she's very much into those high school games. When she believes her boyfriend is dead, she jumps on Squall within the hour. That's horrid. I dont think she'd be loyal at all... and that would destroy poor Squall after he'd given his heart to her.

Selphie - Eh... what everyone else said. She'd say Booyaka too many times and he'd sock her.

Quistis - She's the best of the lot, but she had a tendency to be a bit too dramatic about liking him. I'm a big fan of drama-free relationships. (So why cant I have one!?)