Without a doubt, Obi-Wan's toughest opponent was the Chosen One himself. In a fight that had the entire galaxy on the line, Obi-Wan bested his former Padawan in an epic and emotional showdown.
Obi-Wan Kenobi's most powerful villains in Star Wars include his greatest enemy Darth Vader and less well-known ones like Darth Krayt.
Is Obi-Wan Kenobi More Powerful than Darth Vader? There just isn't any way that in an even fight Obi-Wan beats Vader. Although Vader is supposed to be one of the strongest force users of all time, we actually haven't had a chance to see him using his full strength very often.
Darth Sidious
In the end, Vader managed to fulfill the prophecy tied to him. As for Darth Sidious, he's by far the most dangerous enemy Vader has had. Becoming emperor of the galaxy and crushing most of the Jedi was proof enough.
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.
Because he was not an active member of the Jedi Order during Order 66, Infil'a escaped execution. Some time later, he faced the Sith Lord Darth Vader wielding a green lightsaber. Infil'a put up a fierce fight against Vader, almost killing him by throwing the Sith Lord off of a cliff.
Who is a better duelist Obi-Wan or Anakin? His defeat of Anakin on Mustafar puts him over the top at #1, but that was not all he did. He also bested General Grievous on Utapau in the midst of a large chaotic battle. Obi-Wan was not the flashiest and not the most brash, but he was consistently victorious.
Star Wars: Obi-Wan Was More Powerful Than Yoda - and Palpatine Knew It. A Star Wars fan theory suggests there's plenty of evidence in the prequels that Obi-Wan Kenobi was the most powerful Force user.
Obi-Wan Could've Beaten Vader in Star Wars: A New Hope - If He Wanted To. While Obi-Wan Kenobi was frail by the time of Star Wars: A New Hope, he was still stronger with the Force than Vader.
The only thing his mouth is able to speak is four words: “What have you become?” This is the moment where Obi-Wan is faced with his greatest failure: the loss of his apprentice to the dark side.
In Revenge of the Sith, we again see Yoda in battle. He fights Darth Sidious in lightsaber combat and also through the Force as they battle onto the senate floor throwing chairs at each other. While Yoda holds his own in both of these fights, he doesn't win any of them. We never see the greatest of Jedi win a fight.
Anakin Skywalker, the Chosen One, possessed the highest known count in galactic history—over twenty-thousand midi-chlorians—surpassing the potential of Grand Master Yoda and all Jedi.
Darth Vader
One of the most classic cases of “good to evil” known to entertainment, and quite possibly the strongest Star Wars character ever.
In the Star Wars Legends continuity, the founders of the Jedi Order were Jedi Masters Cala Brin, Garon Jard, Rajivari, and Ters Sendon.
Yoda. Yoda was a wise, experienced, and powerful Grand Master of the Jedi of an unknown species and the oldest known prophet in existence (having lived at least 900 years), considered the wisest and most powerful Jedi Master within the Star Wars universe.
Also, all three became lightsaber instructors to many younglings. Yoda was considered to be the greatest swordmaster of his time, alongside the likes of Mace Windu, Count Dooku, Darth Vader, and Darth Sidious.
1. Miyamoto Musashi—Japan's Sword Saint. The life of Japanese samurai Miyamoto Musashi is obscured by myth and legend, but this “sword saint” reportedly survived 60 duels—the first of which was fought when he was just 13 years old.
Obi Wan is one of the most powerful Jedi to have ever lived. He is the best defensive duelist in galactic history according to Mace Windu and numerous factbooks. He had a low sensitivity to the force but mastered it to his fullest potential worshiping the force as opposed to bending it to his will.
This information comes to light form the comic series Darth Vader: Dark Lord of the Sith by Charles Soule and Giuseppe Camuncoli, in particular issue #7. Palpatine admits to Darth Vader that the Jedi he actually feared most was none other than Jocasta Nu.
It appeared that Darth Vader was more machine than we thought. His armor could be hacked and controlled by a device. In a turn of events, Darth Vader's right limb holding his dangerous scarlet lightsaber was moving of its own accord toward his neck. This was a dangerous weakness indeed.