Ok hear me out but a fly
Just think about it right, you have no consciousness so no thoughts nothing just getting to whiz around as a fly. And unlike a bird or any other flying animal that may die some horrific death as prey, they don't feel pain so no risk there. And yes you may be thinking "but fly's are gross" but you have no consciousness to perceive that therefore u won't know or care as a fly. And they end up dying in like a week or so anyways so not like ur stuck as one for the rest of eternity.
I love getting asked this question and am very passionate about my fly and answer lol.