6. Floyd Mayweather Jr.
If there was a trash talking heir to Muhammad Ali's marvelous boxing throne, it would be Floyd Mayweather, Jr. He exhibits everything you look for in a great talker: supreme talent, unmatched confidence, an overarching theme of humor, and last but most definitely not least, that "I don't give a fuck" attitude. He's ethered De La Hoya, Pac-Man, Victor Ortiz, and countless others to the delight of HBO 24/7 viewers and it doesn't look like he's quite done yet. And let's not forget about the infamous post-fight interview with Larry Merchant. Can you imagine what he'd do if he knocked out Pacquiao? He might buy out Broadway and have them reenact it nightly for a month.