We'd lose the remaining wolves on the planet...
Or we'd lose the remaining lions, tigers, jaguars...
I'd lose one of my two pets.
I don't like this scenario...
From a "for humanity" standpoint, I'd have to save the dogs. They've been our companions for years and are much more cooperative in working with humans than cats are.
If infused with human level intelligence, dogs would be more likely to live alongside us while cats would immediately start determining how to conquer us.
Though with no cats, we'd lose LOLCats too!!!