Darth Vader is Clearly the More Powerful Force User Between Darth Vader and Obi-Wan, it's pretty clear that Vader is far more powerful with the force. After all, he pretty easily used the force to stop a starship from taking off in the previous episode, and manhandled Kenobi throughout the majority of the show.
While Dooku was able to defeat Obi-Wan, nearly killing him, he could not best Anakin. At the urging of Chancellor Palpatine, the young Jedi beheaded the Sith Lord. Anakin carried an unconscious Obi-Wan on his back, and the three returned to Coruscant.
Obi-Wan was physically struck down in death by Darth Vader in the Original Trilogy. This key moment in the Originals satisfied the question with an answer: in physicality, Obi-Wan may be stronger than Anakin, but Vader is stronger than Obi-Wan.
Obi-Wan Kenobi was one of the most talented and powerful of his generation: He won against Darth Maul. He won against Grievous. He won against Anakin, even when Anakin was enraged like hell.
Obi-Wan Kenobi is by far one of the best duelists in the prequels. He may not be flashy or impressive with a saber like Mace Windu, but he has a consistency to him that almost everyone else in the galaxy respects. Anakin Skywalker, who is likely the most powerful duelist, worshiped Obi-Wan as the perfect Jedi.
Darth Sidious was also one of the greatest and most skilled Sith swordmasters, as he has mastered all the seven lightsaber forms, all their stances and techniques and is capable of using each form equally effective ambidextrously.
Jedi Master Yoda is the most powerful of them all. This should come as no surprise, as he was the head of the Jedi Order in the prequels and was revered for his abilities during the original trilogy. Yoda's power is unmatched and was a real threat to Darth Vader and the Imperials.
In Revenge of the Sith, set three years later, Obi-Wan is now a Jedi Master and a member of the Jedi Council, as well as a General in the Grand Army of the Republic.
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.
The Force: Kenobi was extremely powerful, and had an extremely strong connection to the Force, and was one of the most powerful force users of his time. Though Kenobi did focus largely on Lightsaber combat, he was also very skilled and powerful in use of the Force.
Aside from agility and telekinesis, Yoda could absorb and redirect Force attacks, like lightning. Because of his higher understanding, he would easily overcome Darth Vader in a fight, though that doesn't mean it wouldn't be a difficult battle.
One of the main reasons why Yoda would've won against Anakin is simply because he was far better trained than him. Yoda could see the moves his opponents were going to make before they made them; therefore, battling against Anakin would've put him at a far heavier advantage.
In Star Wars Legends and Canon, Galen Marek (Starkiller) is the only Jedi (other than Obi-Wan Kenobi) to put a beat down on Darth Vader/Anakin Skywalker.
Vader still killed Obi-Wan, but it was described in much more detail than Vader just simply cutting down Obi-Wan. This was the passage: “[Vader] lunged forward, feinting, and then slashing in a deadly downward arc with the saber. It struck home, cutting Kenobi cleanly in half.”
He slays Sidious and returns to Obi-Wan, begging for atonement by execution, only to be met with true forgiveness instead. But just as this fantasy Obi-Wan refuses to strike his former friend down, Vader refuses to turn his back on the dark.
Darth Vader's death wouldn't only harm the Galactic Empire's war effort against the Rebellion, but it would also necessitate that Emperor Palpatine, as the Sith Lord Darth Sidious, finds a replacement for his fallen apprentice.
While Obi-Wan Kenobi was frail by the time of Star Wars: A New Hope, he was still stronger with the Force than Darth Vader.
Darth Sidious / Emperor Palpatine
Darth Sidious was one of the destructive maniacal Sith lords and the most powerful character in Star Wars.
The real reason for Obi-Wan's victory, though, may have been that he was the better fighter. While Darth Maul's moves were flashy, Obi-Wan eventually proved himself as one of the best duelists in the galaxy, and his fight with Maul was just the awakening of his skills.
#1 – Yoda. Yoda is widely considered to be the greatest Jedi of all time, and with good reason. He is a master of the Force, a skilled warrior, and has an unmatched wisdom that comes from centuries of experience. He is the embodiment of what it means to be a Jedi, and his legacy lives on long after his death.
In the original Star Wars: Episode VI – Return of the Jedi screenplay, Obi-Wan did have a brother, and it was none other than Owen Lars (Joel Edgerton)—Luke Skywalker's step-uncle and Anakin's step-brother.
Biography. Legend had it that Yoda—a Jedi who became Grand Master—was trained by N'Kata Del Gormo.
1 Darth Sidious
There has been no Sith, as powerful, meticulous, nor as evil as the Emperor himself, Darth Sidious. As previously mentioned, Sidious trained in the Dark Side by Darth Plagueis before Sidious killed Plagueis in his sleep, making Sidious a Sith Master.
Plo Koon. Wise and compassionate, Plo Koon was one of the most effective Jedi masters, genuinely caring about the clones he commanded.
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.