The Jedi have been protecting the Galaxy from harm long before the Sith reared it’s ugly head. In canon, the first Jedi studied on the planet of Ahch-To, and in Legends the Jedi studied the philosophy of the ancient Je’Daii on the planet Tython (located at the very center of the galaxy). Whether in Legends or in Canon, some of the most powerful Force wielders held true to the light side of the Force which tempered their skills until they became legendary heroes in their own right. Here are some of the greatest and most powerful Jedi to have walked the galaxy.
Trained by Count Dooku himself, and master to Obi-Wan Kenobi; Qui-Gon Jinn would affect the Jedi of the galaxy tremendously with his study of the Force. He was an amazing student of what he called “The Living Force”. Many nights would be spent in meditation, unraveling secrets of the Force that none before him had discovered. He specialized in using the Force to alter and persuade the minds of others and his skill with a lightsaber was one to marvel at. After his defeat at the hands of Darth Maul (Star Wars: The Phantom Menace) he transcended humanity and became and immortal Force ghost. It was he who taught Master Yoda and Obi-Wan Kenobi how to master this technique and truly become one with the Force; something never before seen in the Star Wars canon up until this point.
Mara Jade Skywalker
Mara Jade is a Jedi from Legends who was found at a young age by Emperor Palpatine and trained as his personal assassin aside from Lord Vader. She is a peak example of how skill and training can forge one into a powerful warrior. After the fall of the Empire, Mara Jade remained loyal to the cause and went after Luke Skywalker to carry out her masters last order. Upon meeting Luke he was able to turn her from the dark side and they ended up marrying. She is said to have been one of the greatest duelists of her time, and her ability to sense present danger surpassed her husbands. Her training as a stealthy assassin of the Emperor came in handy while on missions with Luke fighting for the good of the universe. As well, she helped Luke train a new generation of Force users in a reborn Jedi Order.
Alot of what makes Master Mace Windu so powerful is detailed in Legends, but still in Canon he is a legendary master of the Force in his own right. In Legends, Windu could see shatterpoints in the Force allowing him to vividly see how his actions would affect the future. While a padawan, he saw a vision of himself wielding a violet colored lightsaber. A crystal of that color was extremely rare, but it would be Windu to find the parts and build his lightsaber from his visions. Windu became the youngest Jedi to be inducted into the Jedi Order and showed his prowess in the use of a lightsaber by inventing the lightsaber Form VII: Vapaad (allowing Jedi to channel their own inner darkness into a duel, accepting the fury of the opponent). Mace Windu, though a little arrogant, always kept his feelings in check and remained a stalwart member of the Jedi Order until the very end.
There’s something great about Sith assassin’s turning away from the dark side to fight back at the masters who controlled them. In Legends, Galen Marek was found by Darth Vader on the planet of Kashyyyk. Vader killed Galen’s father, Kento Marek, who was an exiled Jedi in hiding. Vader sensed a very powerful Jedi on the planet and figured it was Kento, however it was little Galen that Vader saw promise in. Vader took Galen and trained him to be a purely brutal assassin, giving him the moniker of Starkiller. Ignoring the more ethereal aspect of the Force, Starkiller focused solely on lightsaber combat and using the Force to kill others. He killed many Jedi for Darth Vader until he met Jedi Master Rahm Kota, and feigned interest in the light side of the Force. However, in actually studying the Jedi order and with the help of Kota, he joined the newly formed Rebellion and became a Jedi Knight. He went straight for the Death Star and almost destroyed Vader and nearly killed Palpatine, but it was here that he would meet his end in noble sacrifice for the Rebellion and his beloved friends. He remains one of the most vicious lightsaber wielders and most skilled in the more dangerous aspects of the Force. Seen in The Force Unleashed video games.
When the Jedi Civil War rocked the galaxy, Bastila was only a padawan. Her skill in Battle Meditation however was unrivaled and she was instrumental in the battle to terminate Lord Revan. As a padawan she boarded Revans ship, defeated him, and brought him to the Jedi Council where they wiped his memory. Then she and Revan set out to stop the Sith from gaining access to the Star Forge and destroying the Republic. She would help mentor Revan as he regained his memories. They shared a powerful Force bond, and as he began to remember how to use the Force she helped him rejoin the Jedi and fight against the Sith. After Malak’s defeat they were married. This was in much opposition to the Jedi council since they viewed Bastila as their finest student yet. Yet the Jedi permitted it on condition that they did not spread their rebellious teachings to others. Revan and Bastila’s descendants would be among the greatest of Jedi to live (one of whom being Jedi Grand Master Satele Shan).
Ever wonder what it would be like if Han Solo was a Jedi? In Legends we have the story of Kyle Katarn, Imperial Stormtrooper turned Rebel turned Jedi Master. Kyle Katarn defected as a stormtrooper in order to join the Rebellion and was integral in destroying the Dark Trooper project. With a charmingly dry sense of humor and a knack for strategy he was a decorated Rebel, and at the end of the Galactic Civil War, Kyle went on to help form the New Republic. In a dream he was visited by Jedi Qu Rahn and told of his Jedi heritage which set him on the path to become a Jedi. Kyle found Qu Rahn’s lightsaber and went out seeking the Valley of Jedi where he confronted dark Jedi and ancient foes alike. He honed his Force skills and became a Jedi Knight. Kyle is known for employing dark side Force powers when needed in addition to using the light side. He would employ variations on many different lightsaber techniques, and can be seen wielding both a lightsaber and a blaster. He became a member of the New Jedi Order and is a trusted associate of Luke Skywalker himself.
Obi-Wan Kenobi is one of the greatest Jedi to have lived. He was known during his time as the greatest duelist on the Jedi council, and with the mind of a cunning strategist he became one of the most prominent generals during the Clone Wars. Despite his dislike for flying, as a padawan he was noted as an excellent pilot and expressed interest in the Jedi Starfighter program. He mastered many lightsaber forms and specialized in mind tricks just as his master Qui-Gon Jinn had. He is an exceedingly well rounded Jedi. He had many allies and formed many friendships during the Clone Wars. He trained Anakin Skywalker, the chosen one, and witnessed his eventual fall to the dark side. He spent the majority of his life as an exile on Tatooine guarding Luke Skywalker who he would also train. Eventually he would become one with the Force and revive as a powerful Force Ghost. No Jedi has influenced the fate of the Galaxy more than Obi-Wan Kenobi, for without him, Anakin would have fallen to the wayside far sooner and Luke would never have been able to bring down the Empire.
Yoda was the oldest Jedi Council Member at his time at nearly 900 years old. Not much is known about his past, but he will be remembered forever. He was a legendary Jedi Master whose mastery in the Force was renowned throughout all of galactic history. Though he is only a little taller than 2 feet, he is the wisest of Jedi and his teachings permeated through all those trained on Coruscant. His worth as a Jedi master goes far beyond his skill with a lightsaber because Yoda truly is a master of the Force (though when he needs to pull out his lightsaber he is a formidable opponent). He was a renowned and respected leader in the Clone Wars, and witnessed the fall of the Republic and the Jedi order. After the purge he exiled himself to Dagobah, a planet strong in the Force and largely uninhabited, as not to draw the Empires attention to innocent civilizations. Even with all these attributes, he is still a peculiarly pleasant individual; strict when he is needed to be and grandfatherly at other times. Even at the very end of his life he found peace within the living Force.
Anakin Skywalker technically is the most powerful of Force users, with the highest midi-chlorian count of anybody. However, he spent the majority of his life as a Sith Lord and Jedi Murderer, though he does become a Force ghost, and is redeemed. That being said, the greatest of the Skywalkers is Luke Skywalker. Luke had no training whatsoever and hardly any practice of the Force when he was called upon to aid the Rebellion. Even when Luke fought Vader for the first time he was technically just a padawan.
In Legends, Jedi would have visions of Luke Skywalker and his father long before they were born. Detailed in Canon and Legends alike, Luke was impulsive and reckless like his father. However, he tempered himself with much discipline and training until he was a pensive, calculating, and powerful grand master of the Jedi. His ability to see the future surpassed that of many Jedi before him and his skill with a lightsaber was unique (focusing solely on defense until a weakness was to be found and exploited). Not only that but he was known as a bold leader, and an empathetic friend, going to great lengths to ensure those he cared for were protected. He is everything his father was, but overcame his weaknesses and did not succumb to the dark side of the Force, though in Canon he was tempted even during his training of the Knights of Ren. It was Luke who ushered in a new era for the Jedi. He and his sister Leia would go on to shape the New Republic. Moreover he largely rebuilt the Jedi and Republic with hardly anything to go off of besides what he could find in ruins and from the occasional Force ghost chat. Anakin may have brought balance to the Force at the end of his life, but Luke spent the rest of his life maintaining that balance and that is the very greatest and noble of Jedi.