Which is frankly moronic. How could you determine the best swordsman from a continent with 8000 years of history? Did they have highlight reels?
People can't agree who is the best boxer in just a hundred years of history, and that's in the modern age with thousands of hours of footage, statistics, boxers giving their own opinions etc.
People within the ASOIAF universe considering Dayne to be the "greatest swordsman ever" is just hype. The human need to make your time on Earth seem the most important time period that ever was. So your swordsmen are the best swordsmen and your war is the greatest war to end all ages etc.
Dayne(like Jaime or Barristan) is natural talent trained to the peak of human ability. That doesn't make him the greatest. There are others like him. And there are others that have natural talent but no formal training(like Bronn or Karl from the show) and those that are trained at a castle to be a warrior but aren't genetically gifted(i.e: Jorah Mormount or any run off the mill knight).
In fact if there was any one person who had the claim to be the greatest warrior - if such a thing were possible - it's probably Gregor Clegane, and that is because he was just a genetic aberration. Physically he was a freak of nature, he was trained from childhood to be knight, and he was a stone cold killer. He was a perfect storm, but even he was put down by Oberyn.
THERE IS NO GOAT!
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Oh, and Syrio is a top notch swordsman. He was the Musashi of ASOIAF, an extremely smart and perceptive warrior who had swordsmanship down to a science and engaged in life or death duels his whole life.
The fact that he couldn't win against the best knights of Westeros(arguable) is due to the fact that he adapted to his own environment, Braavos. Knights are well armored because they fight on battlefields, bravos are lightly armored because they fight on ships and 1 on 1 duels. A knight would also be helpless in the swamps and bogs of the neck while sneaky crannogmen shot poisoned darts at them, because the crannogmen are better adapted to their environment.
Ever hear the expression "Game recognize game"? In the books, Bariston Selmy (who is regarded as a legendary fighter) said that Dayne is the best. Not to mention other legendary fighters like Jaime and Ned said the same thing.
Why are you so adamant against this? Is this touching some kind of insecurity in you? I already know you're not a stable poster, dropping racist shyt and disappearing for a time before reappearing.