Anakin is one of the best, if not the best, lightsaber duelist across the 9 movies. Even aside from his connection to the Force, he showed immense skill, ingenuity, and power when engaged in lightsaber duels, such as his fight against Count Dooku.
Jedi Battlemaster Cin Drallig and Grand Master Yoda had knowledge and mastery of all seven forms, including Juyo, befitting Drallig's role as lightsaber combat instructor at the Jedi Temple and Yoda's reputation of having mastered all forms of lightsaber combat as did Anoon Bondara, another lightsaber instructor.
Yes, Darth Vader is the greatest duelist in the Canon Disney. Despite being naturally extremely talented, Anakin Skywalker was initially lax with his lightsaber training, though he believed that he could rival the Jedi Masters.
Vader held respect for Tarkin which is clearly shown and the only case in which Tarkin outranked Vader would be the case in which Vader was in the Death Star or within Tarkin's Oversector which he likely was as Tarkin was Grand Moff of the Outer Rim Oversector, the largest one.
A master duelist of the Old Republic. Obi-Wan Kenobi was considered to be one of the greatest Jedi swordsmen of all time. A practitioner of Form III: Soresu, Kenobi was considered the greatest master of the form ever, just as Count Dooku was considered the greatest Makashi practitioner ever.
Sokan was a form of lightsaber combat. Developed by the ancient Jedi Knights during the Great Sith War, Sokan combined tactics that allowed for evasion and mobility with the kinetic motions of Form V combat.
Notable practitioners
Other than Lucien Draay, Meetra Surik, Obi-Wan Kenobi, and Kit Fisto, Shii-Cho had many advanced and/or specialist practitioners. In more recent years, the form was mastered by the Jedi swordmaster Cin Drallig along with the other six forms.
The Forbidden Forms were forms of lightsaber combat used by the Sith during the Sith Wars. According to the testimonies of the Jedi Cervil the Uncanny, lightwhips—a lightsaber variant with a flexible blade—were used to defend against Sith Lords who utilized the forms.
Revan was considered to be among the best duelists of his time, with a mastery of all seven lightsaber forms, all of their variants, in both regular and dual saber style. In canon, either Yoda or Sidious. They were repeatedly stated as being the best swordsmen of all time.
1. Darth Sidious (Star Wars: Episode I – The Phantom Menace) Truly, the most powerful Sith Lord was Darth Sidious, better known in his public persona of Chancellor (later Emperor) Palpatine. Through cunning and manipulation, Sidious killed his master to claim the mantle of Dark Lord of the Sith.
Yoda mastered the original variant known as Juyo. Both of them were able to fight with Palpatine on equal ground, matching him blow for blow. It is stated that Yoda beat Mace in a sparring match.
There are 7 forms of lightsaber combat, but Soreso, Shein, and Vaapad are the most effective. Soreso, Vaapad, Shein, are the most effective forms because they are all strategic and have their strengths and weaknesses.
Form VII: Juyo (or Vaapad)
Form VII is the last known form of lightsaber combat and is known to be the most aggressive. Jedi Master Mace windu is the main Jedi known to use this form of combat because Form VII is the most aggressive and only the most Force-sensitive individuals can execute this form successfully.
Form II relied on careful and controlled strikes instead of power and strength. Count Dooku was a master of this form and trained the Sith assassin Asajj Ventress in its use, though hers was less elegant than her master's.
There were seven known forms of lightsaber combat: Form I, Form II, Form III, Form IV, Form V, Form VI, and Form VII.
Through the Force, Yoda was considered to have mastered Form IV to its highest level. He used it in almost all of his battles, and his mastery of the style caused others to describe him as virtually unstoppable against most opponents, including Separatist battle droids, despite his small size and advanced age.
Obi-Wan Kenobi was highly skilled in Form III. Over the course of the Clone Wars, Kenobi continued to develop his skills.
Yoda was best in Ataru(Forme IV) and probably one of the most experienced duelist ever. There is also Jedi General Obi-Wan Kenobi who was an absolut master of Soresu(Forme III), deffensive form. He knew how to defend and he won General Grevious but still he had few weaknesses.
This isn't to say that Mace Windu isn't powerful when it comes to the force. He's on par with Darth Maul and is more powerful than Qui-Gon Jinn. But, Obi-Wan is still the stronger Force user which makes him a powerful combatant.
Emperor Palpatine/Darth Sidious
As he states in Episode III: Revenge of the Sith, “the dark side of the Force is a pathway to many abilities some consider to be unnatural,” and there is no one better at it than Emperor Sheev Palpatine aka Darth Sidious.