It's because compared to Hina and Koto, cat girl knows that she's insane herself, the other two were in denial of being a Gachikoi. This one though knows and embraces it
At the very least in terms of semblances of sanity and the like, it’s:
1. Koto
2. Rihoko
3. Cat Girl
4. Hina
Koto at least tried taking responsibility for her dishonesty and crazed actions with deceiving Cosmo and doxxing Yuuko, ( the two and Nao have even become a trio of friends.)
Rihoko distanced herself from the roots of her obsession & problems and began making strides to improving herself and finding better interests and making new relationships.
Hina, Harumi, and Ringo are so insane. The former two blame Subaru and Cosmo for ‘making them fall in love’ and cannot accept the real them or any changes that they might make about themselves.
Ringo I thought she’d be sane, but no.
All in all, I only really like Koto and Rihoko. Cat Girl I still need to see about.