Well adjusted I'd probably go for Ayane honestly, really has her shit together and matures a lot over the story,
"Normal" would have to be Rin / Otoha IMO, two teenagers doing dumb love stuff.
Least fucked up should be it's own category and I don't even know who to put here, maybe Touka? She's getting groomed obviously but everything else is reasonably normal, she's not too weird, doesn't have any wild shit going on either.
Ofc im ignoring side chrs cause they'd win all categories in a boring way.