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.
He was Force-sensitive, and therefore taken from his family and inducted into the Jedi Order as a child. Raised in the Jedi Temple on the planet Coruscant, Kenobi was assigned to Jedi Master Qui-Gon Jinn.
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.
Obi-Wan Kenobi's greatest feats of strength are proof that he was the most powerful Jedi of his era. Obi-Wan Kenobi was one of the most well-known Jedi of the Star Wars universe, having established his reputation in the original film.
No. Obi-Wan was not as strong as Anakin. But unlike Anakin, Obi-Wan did not rely upon a lightsaber style requiring great strength and aggression. Instead, Obi-Wan was the master of Soresu, a highly defensive style that relied upon efficiency of energy.
Darth Vader was the stronger of the two by far. However, as with most lightsaber duels, the victor is the one with the greater connection to the Force. In their final fight of the series, set about nine years before the events of A New Hope, Obi-Wan hurled a barrage of rocks at Vader.
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.
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.
#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.
While this saga is ultimately the story of the Skywalkers, Obi-Wan is arguably the best and most pure Jedi to ever come out of it.
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.
He explains as much to a young Leia in Season 1, Episode 2: "If I use the Force, it will draw attention to us." That means he likely never practices his Force skills. No telekinesis, no meditation and certainly no lightsaber use. Even the Jedi mind trick needs to be used only in emergencies.
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. It's nigh impossible to quantify the Force in Star Wars.
This might seem unexpected but it's worth noting that there are a couple of things that factor into Obi-Wan's inability to effectively stand his ground. Firstly, he hasn't fought in years. In order to hide from the Empire, he needed to keep a low profile. This means that he's not in his best fighting form.
Plo Koon and Kit Fisto are speculated to have had around 13,000. Obi-Wan Kenobi is actually a great example of a Jedi with this level of midi-chlorian density. He had a midi-chlorian count estimated to be about 13,000.
Arguably, some of the rarest types of Jedi were the so-called Iron Knights. These are members of the Shards species - crystals with a brain of their own. They were Force-sensitive and all trained under the tutelage of Jedi Master Aqinos. The Shards had droid bodies, similar to that of General Grievous.
Plo Koon. Wise and compassionate, Plo Koon was one of the most effective Jedi masters, genuinely caring about the clones he commanded.
If we're to come to a definitive decision on who the strongest Jedi ever is then we have to consider more than their physical skills and strength. Master Windu could be the strongest Jedi ever, he's strong, trained, wise and proved his abilities in combat as well on the Jedi council.
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.
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.
Lord Sidious was an unparalleled sith whose skills are measurably above Obi-Wan's. Specifically, he was able to defeat Yoda and force him to retreat from the Senate floor.
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.
Originally Answered: Could Obi Wan defeat Palpatine in a duel? No.. He can not.. And BOTH Yoda AND OBI WAN himself SAID SO both in the movie and the book Revenge of the Sith.