Luke Skywalker's status as the most powerful Jedi primarily comes down to his abilities versus Anakin's squandered potential.
In a 2005 conversation with Vanity Fair, George Lucas shared Anakin was on the path to becoming the most powerful Jedi. But, after he took a turn towards the dark side and lost his limbs in his duel on Mustafar against Obi-Wan Kenobi and was given a partially robotic body, it significantly stunted his powers. Lucas added that the incident led to Emperor Palpatine focusing on turning Luke to the dark side, knowing Anakin couldn't reach his full potential and surpass his abilities in his new form. In a DVD commentary for "Star Wars: Episode V — The Empire Strikes Back," Lucas elaborated on the dynamic, sharing Vader planned to turn Luke to the dark side so they could overthrow the Emperor together. He said Anakin would have done that without help before losing his limbs, but he lost his upper hand because of his condition. Lucas stated Luke was Vader's "hope," and the Sith saw his son as a mechanism for his "lust of power."
Speaking with Rolling Stone in 2005, Lucas commented Darth Vader's plans were significantly derailed by his traumatic fight against Obi-Wan and that instead of becoming stronger than the Emperor, he was like Count Dooku or Darth Maul. In the "Star Wars: Episode VI — Return of the Jedi" DVD commentary, Lucas shared that Emperor Palpatine wanted Luke to kill his father, knowing he could be a better apprentice. Thankfully, Luke wasn't swayed by the dark side.
