If that's your criteria you should roll with bonobo.Dolphins get it on for fun - no brainer
I've always said I want to be a pampered house cat in my next life. Sleep all day, fed regularly to where you get kinda chubby, can throw up wherever and whenever you want just for fun, and can still fuck up a dog if necessary. I couldn't play video games or masturbate, but I also wouldn't realize I was missing them, and otherwise life would be perfect. I might lose my nuts, but again, I wouldn't know any better.