Darth Vader defeats Darth Maul. The two Sith Lords engaged in a lightsaber duel, going through the volcano and onto a bridge situated over a river of lava, which collapsed, though they both survived and continued their battle.
In the end, Vader reigns supreme against the reborn villain as his hatred drives him to be named the winner of the fight. In the end, Darth Vader's inner hatred and darkness made him the winner of the epic battle against Darth Maul.
Regardless, based on the season 7 of The Clone Wars, and the fact that Darth Maul was aware of Anakin Skywalker's future and his role as the Chosen One, it is very likely that Darth Maul indeed feared Darth Vader to some extent, and preferred to avoid a direct confrontation with him, at least, on his own.
By the time of Episode 3; Anakin is in his prime, and already one of the Jedi Order's most powerful “masters” (although technically still a knight), just behind Obi-Wan, Windu, and Yoda. Maul wouldn't stand a chance.
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.
The only Sith Lord who actually killed Vader, Darth Sidious kept his apprentice in line for over two decades. His true advantage was Force lightning, a power which would wreak havoc on the suit keeping him alive.
Infil'a put up a fierce fight against Vader, almost killing him by throwing the already damaged Sith Lord off of a cliff. Despite severe damage to his suit, Vader survived the fall, and repaired himself with parts from Infil'a's droid, Arex.
Star Wars Rebels lead creator Dave Filoni even admitted that Maul and Vader were meant to have a fight, but he felt it would take away from the battle with Ahsoka. But as things stand, Star Wars not only lacks a fight between Vader and Maul, but the two have never even spoken to each other.
Summary. Darth Vader's intense hatred extends beyond Obi-Wan Kenobi and himself to Emperor Palpatine, as revealed in Star Wars: Darth Vader #39. Vader had to tap into his deep-rooted hatred for Palpatine to overcome a deadly Scourge and destroy a Clone Wars-era droid.
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.
It's already been shown in the source material… more than once… that Darth Maul is not on Darth Sidious's level. Every time he dueled Sidious as his apprentice (in Legends) he got easily defeated. In the show Star Wars: The Clone Wars, Palpatine takes on Darth Maul and Savage Opress simultaneously.
Had they fought one another at their full potential, Maul's exceptional lightsaber skills would have been difficult for Dooku, but Dooku's knowledge of the dark side of the Force would likely have prevailed.
He just wasn't explicitly taught it, or dark side sorcerery more generally. His training was focused on the skills of a Sith assassin, being an overwhelming lightsaber duelist. You need real legs to be able to force-siphon the electric current from the ground. That's why Maul or Vader can't use lightning.
There are certainly scenarios where Darth Vader would have the upper hand in a duel with Yoda, but in most cases, Yoda would be the more likely victor. Vader wields absurd levels of Force power during his dark side prime that would certainly rival Yoda's own abilities, but likely not exceed them.
Given the years between these comics' publications, it's hard to tell if Gillen built this argument intentionally or not. Regardless, the core concept is still true. Thanos wields more power and authority than Darth Vader, existing as a stronger and more capable villain overall.
Darth Maul could have killed Anakin Skywalker at least twice and therefore prevented Darth Vader from being created, but that does not mean he would have been powerful enough to stop Darth Sidious' rise to power.
When it comes down to both combatants in their prime, Yoda was superior to Darth Vader. That debate extends even further to prime Anakin Skywalker as well. He would have been outmatched by Yoda for many of the same reasons Obi-Wan outmatched him, and more.
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.
