my first instinct was to say cat! only because i'm so incredibly jealous of the life they live, and i see it more now that i have kittens of my own now. eat, sleep, drink, play, repeat....i'm so jealous i wanna be them sooo bad. i also think it'd be fun to be any type of bird that can fly, sorry penguins, ostritches etc but i imagine it's super freeing getting to fly wherever you want at any time