ok here is how it is, as the question states who is the best SWORDSMEN out of them its definatly will considering thats what the CREATOR claimed
now the best FIGHTER is a slightly differant matter and harder to judge considering they all bring somthing unique to the table
Will- most skilled swordsman
Jack- most clever/cunning fighter
Hector- most experienced fighter considering his age and the early age at which he started fighting
Jones- special powers including being notoriously hard to kill.
Will is definitely the best swordsman - when it comes to following the rules as every gentleman would. Will doesn't fight like a pirate, which of course, is a problem since the movies are fraught with them. Jack would never have won against will in CotBP UNLESS he cheated, which means that Will can be defeated, but only if his opponent fights dirty.