This. Definitely. Wladimir's straight right takes a good second place. Vitali's punches are not that strong as individual punches, his strength is more in the volume of the punches.
that would be Joe Calzaghe...46 fights,46 wins with 32 ko..and that's only by slapping people..imagine what he can do if he ever throw a real punch..he may have real one punch kill power.to bad he retired