Kinzie looks to be the only REALISTICALLY believable girl in terms of physical appearance. At least in her artwork. I was a little sad to see she ended up having huge breasts like EVERY OTHER freaking girl in the game. :/
If we're going by the artwork, Kinzie for certain, but I haven't met Viola yet so I can't say it'll stay that way. But like someone else said, nerdy girls are definitely hotter in their own way, and I definitely prefer "cute" to "hawt" any damn day.
Now, in SR2 it would've been Shaundi all the way cause as also has been said, she was easy going and fun loving. I totally sympathize with SR3 Shaundi and you have no idea how much I'd love to give her a hug, but I do think they went just a tad over the top. It's like they turned her into some butch action chick who'd probably break a guy's arm before even responding to a hello.
On the other hand, if you listen to the commercial for Shaundi's TV show, she sounds more like the old Shaundi in terms of personality.
Eh, I'm the kinda person who'd be happy to hang out with all three of them on different levels and just see where it goes from there.