When one looks at Bob Hoover's life and career*, one could make the argument that if he is not the Greatest Ever Pilot, he'd be damn near the number one spot.
As for Yeager, he'll tell you what a great pilot he is, you don't even have to ask.
* Including escaping from a German POW camp during World War Two, stealing a FW-109 and flying it to England.
Come to think about it, Jimmy Doolittle would have been right at the top as well.
One more point about Bob Hoover, I've met Mr. Hoover a few times and a braggart he is not, he always manages to turn the conversation away from about him and to the person he is talking to.