Assuming that they've all aged up enough to not make any of this weird:

Kill - Yuffie
Smurf - Selphie
Marry - Rikku

I actually like Yuffie, but even I know she's annoying and likely to steal from me, so with the lack of an 'avoid' option, she's dead. Selphie... well I haven't actually played FFVIII yet, but she seems nice? And Rikku I'd marry because she's friendly, fun, and a mechanical genius.

EDIT: Fine, I'll do double duty:

Kill - FFIX Mog
Smurf - FFVI Mog
Marry - FFXIII-2 Mog

Where do I even start? I don't know FFIX Mog, so they're dead. FFVI Mog seems fun, but I spent most time with FFXIII-2 Mog. He's nice, and if I ever start to be annoyed by him I could just tell him to turn into a table or something.

Right, next up, the roguish types!

Irvine (FFVIII), Balthier (FFXII) and Locke (FFVI)