Dogs. German Shepherds, Dobermans (uncropped), Akitas, and Yellow Labs/Golden Retrievers to be specific. Best animals ever, especially puppies!
Horses are pretty awesome too. I like the chessnut colored ones.
Cats can go die in a hole. Or get smashed under the wheels of an 18 wheeler. Or maybe even under the tracks of a bulldozer or a tank. Oh! I know! The hole they die in should be created by a bunker buster!
Except for kittens, those are fun to mess around with.