Okay so... On her own merits? Kairi's basically perfect.

Problem is, the universe hates her and will fuck you over to get to her. Or fuck her over directly and make you watch.

Sora and Riku can testify.

Sayori would be very loving and affectionate, but she'd need a lot of support day-to-day. Don't expect her to be the one keeping things up around the house.

shakes fist at nomura

Twilight would be wonderful... when she isn't hyperfocusing on something which may or may not have horrible unintended consequences.

And even if it doesn't, you won't be the focus of her attention until she snaps out of it. Probably something you'll need to negotiate.

Iri already graduated from Wife Academy with flying colors, A+ choice just ask Kiritsugu.

Hayate will be a wonderful, if very busy, spouse. But nobody's going to get anywhere close to that point without both realizing and accepting that Monogamy Was Never An Option.

Iri's only drawback is being doomed by the narrative—

I've got a few of those...