The realistic answer seems to be, yes, Anakin in his prime could have defeated Luke Skywalker (in the current canon) if they battled one-on-one. The main reason behind this is Luke's lack of formal Jedi training, at least when it comes to combat.
And despite Vader's weaknesses, it's not as if Luke was unskilled, as he spent plenty of time honing his connection to the Force after Star Wars: The Empire Strikes Back, and was likely the most skilled lightsaber-wielder Vader had faced in a long time.
Luke had the second-highest potential in the Galaxy's history - right behind his father. Had he unleashed his full potential as a Sith, he'd be utterly unstoppable.
While the Son was extremely powerful in his own right, he ultimately was no match for the powers of the Chosen One Anakin Skywalker until he fully succumbed to the Dark Side and was therefore able to easily best Skywalker in terms of power.
Despite being the Chosen One, Anakin Skywalker was not the most powerful Jedi in Star Wars, as that honor goes to Ahsoka Tano. The Star Wars prequel trilogy focused on Anakin's desire to become the most powerful Jedi, and while he became very strong in the Force, his lust for power drove him to the dark side.
What If Anakin Skywalker DEFENDED The Jedi Temple During Order 66
Is Anakin more powerful than Rey?
Going by potential power Anakin has 20,000 midichlorians that is known of, but his full potential could have been much higher, maybe 30,000–40,000. Palpatine is stated to have 19,000, so I would safely assume that Rey could have anywhere from 12,000–15,000.
This caused him to attempt to assassinate him in his sleep. Needless to say, Kylo Ren is almost definitely a significant threat. However, we cannot definitively say that he is more powerful than Luke. Kylo's powers are vast but they are still highly unbalanced and difficult to control.
Wise, powerful in the Force, and skillful with a lightsaber, Yoda was synonymous with the Jedi Order and trained countless future Jedi. There was no opponent in the galaxy who did not fear Yoda – even Palpatine knew that the little green master could defeat him. As such, prime Yoda could beat Luke.
Kylo lost to Rey in TFA because he was heavily wounded and was holding back against her due to Snoke's request that he bring her back to him alive. He is also stated by Palpatine in the Secrets of the Sith book to be “equally as powerful as a real Sith despite not being one”.
Obi-Wan faced off against Darth Vader four times and physically beat him twice while beating him through his Force development in a third fight. Obi-Wan Kenobi had the high ground that led to Vader's disfigurement and becoming the ultimate Star Wars cyborg.
There are few reasons for this; firstly, the young Skywalker has become more powerful. While he didn't continue his traditional training with Master Yoda, Luke was on the field, practicing what he knew thus far, and honing his skills in the real world.
Kylo Ren is not weak, his potential is certainly as high as any of the Skywalker lineage, but I believe he simply has a misunderstanding of how the Force works, and because of this misunderstanding, he has made himself weaker.
As further highlighted by Vader and Kylo's redemption stories, it was a lesson that Kylo Ren never fully learned himself, which makes Darth Vader the more powerful user of the Force between the two of them in Star Wars.
Vader had to obey his master, so he goaded Luke until he touched the dark side. That's why Palpatine congratulated Luke, saying, "Good. Your hate has made you powerful." Many fans declare that Luke won the confrontation because he nearly killed Vader, but that's technically not true.
The realistic answer seems to be, yes, Anakin in his prime could have defeated Luke Skywalker (in the current canon) if they battled one-on-one. The main reason behind this is Luke's lack of formal Jedi training, at least when it comes to combat.
By the time of Return of the Jedi, Luke is considered a Jedi Knight. But even at this level, his abilities seem to pale in comparison to the average Jedi from the prequel trilogy. Aside from Luke Skywalker, Obi-Wan Kenobi is also weak in the original trilogy compared to himself in the prequels.
Admittedly, Rey skills couldn't possibly be as developed as Anakin's or Luke's. Nevertheless, considering how fast of a learner she is, and how unique the powers she possesses are, it's not a stretch to say that Rey could be a more powerful Jedi than Anakin and Luke Skywalker.
The light side is said to be stronger than the dark, but Palpatine's connection to the Force appears to have grown far stronger in Return of the Jedi. So while Luke may have bested him in terms of athletics, Palpatine's Force-powers could very likely give him the victory.
Kylo Ren's "unstable" lightsaber was designed to kill. Knowing Makashi, he would become a much more dangerous foe as he could disarm and eliminate his opponents far quicker without the need to endure a long, intense fight. Sadly, he didn't learn Form II as there was no one around to teach him during his younger days.
Drumroll please... Move aside, Anakin Skywalker. Master Yoda has risen above all others to claim the top spot as the most powerful Jedi of all time and the true chosen one according to IGN's audience. He won pretty handily as well, as he was victorious in 89,756 of his 95,243 battles and had a win percentage of 94.2%.
George Lucas has stated that while Anakin had the most potential, in the form of a high midichlorian count, Luke Skywalker is the most powerful Jedi of all time — yes, topping Yoda, Revan, Nomi Sunrider, etc. This is due to more refined power.
