I like the theory of the Sphinx originally being carved as the god Anubis. Makes sense. Ancient god of the dead.
I prefer the lion theory because the back of the statue looks more like a lion that the traditional representation of Anubis. One of the theorists also notes that the statue, if it was actually done many thousands of years before the pharaohs built the pyradmids, would have been looking at the Sun during the day and the stars in Leo at night.
Either one is more likely than a small head pharaoh imho.