I voted for the Sci Diet.

Recently, I tried to switch K'Cee over to the Royal Canin. I started mixing it with her sci diet; she ate around the new stuff--totally wouldn't touch it. Then, she decided she liked it. But after a couple days, her stool became hard as a rock; she had trouble going potty. Soooo...back to the sci diet for us!

Clarice and Tinker are both on the light/senior hairball formula. It doesn't cut out hairballs completely, but we have def. seen a difference.