Well as it's been shown so far, Connie is much more likely to remain level-headed while Steven is a great big ball of emotions that constantly pour out all over the place. Likewise, Connie is more refined, and studious, heck, she even plays Civilization 5 which is not something I think Steven would enjoy very much as it is overly complicated.
Sapphire has been shown to get upset, even emotional, crying or shouting in various circumstances, so she's not just constantly calm, but I'm pretty sure Connie lines up more with her coolness than Ruby's fiery personality.
Steven on the otherhand is just as passionate as Ruby, so I'm going with the traditional view the show seemed to portray in Here Comes A Thought.