Vader wins over Revan.
I would be using an excerpt from the novel The Old Republic: Revan
The Emperor rose to his feet, his robes smoking and singed where the lighting had struck him. His black eyes flashed red, and he raised both hands high above his head.
Revan knew he was gathering his power to unleash a swirling storm of pure dark side energy, just as Nyriss had done. The Jedi quickly calculated his options. Realizing he couldn't close the gap between them quickly enough to stop the assault, he gathered his own energy and spread his hands before him, ready to catch and absorb the Emperor's attack.
A dozen bolts of purple lightning arced from the Emperor toward him. Revan tried to draw them in and contain them, but the Emperor was infinitely more powerful than Darth Nyriss had ever been.
Revan's body was engulfed in agony as the electricity coursed through his body. His skin began to boil and blister, the flesh of his face melting and sticking to the superheated metal of his mask as the Emperor poured more and more power into him.
Through the haze of indescribable pain, he saw T3-M4 rushing in to help him. The droid let loose with his flamethrower, bathing the Emperor in fire. At the last instant the Emperor cocooned himself in the Force to save himself from being incinerated, breaking his focus on Revan.
The Jedi collapsed to the ground, burned but still alive, the hilt of his extinguished lightsaber lying on the floor less than a meter beyond his grasp.
Almost too weak to move, Revan managed to raise his head just in time to see the Emperor turn on the brave little astromech. A tremor rippled through the air as the Emperor unleashed the full power of the Force against the defenseless droid.
T3 never stood a chance. The little droid exploded into a million pieces, internal circuits and external casing obliterated in a single instant.
"No!" Revan screamed from the ground as bits of his friend rained down on him in the form of unrecognizable shrapnel.
He tried to rise, but his injured body refused to respond. Instinctively, he called on the Force to give him strength and heal his wounds.
The Emperor was approaching him with calm, purposeful steps. Once he reached Revan's side he calmly bent down and picked up the Jedi's fallen weapon, igniting the blade.
The healing properties of the Force were powerful, but Revan's wounds were severe and he needed more time to restore his strength. Helpless, he could only stare up at the Emperor as he raised the lightsaber to deliver the killing blow.
* * *
Even as she called to Scourge to help, Meetra was already sprinting toward the far end of the throne room. Scourge hesitated before joining her, taking a moment to survey the situation, memories of his vision of their failure still fresh in his mind.
What he saw was not good. Revan was being electrocuted, his body spasming uncontrollably as the Emperor blasted him with dark purple lightning.
Revan's astromech launched a jet of flame at the Emperor, freeing Revan, who collapsed to the ground. In retaliation, the Emperor disintegrated the offending droid, strode over to where Revan lay, and picked the vanquished Jedi's lightsaber up off the floor.
It all happened in the space of only a few seconds. Meetra was moving fast, but she was too far away to stop the Emperor from eviscerating the prone Jedi at his feet.
I've highlighted the relevant parts. Unpacking the first layer of Vader's eminence, we can make a comparison of durability:
- "In the space of only a few seconds," Revan begins "spasming uncontrollably" and "collapse
to the ground" under the Sith Emperor's assault. In contrast, Vader literally walks through the Galactic Emperor's barrage for close to ten seconds never breaking stride, as seen from the movie (link).
- Revan "gathered his own energy and spread his hands before him, ready to catch and absorb" as well as "draw in and contain" the Sith Emperor's lightning yet the result was the same. Vader "focused solely and sightlessly on his will" "to defeat the evil embodied in the Emperor" while "ignoring" everything else, meaning that he was focusing all his energy into killing the Emperor rather than defending from his attack with a proper Force defense unlike Revan, which is made all the more clear by their brachial positions: Revan's being an overt sign of tutaminsis while Vader's being bereft of any defensive gestures, indicating the only Force shield he did have was likely an instinctive, subconscious one, much weaker than an active barrier.
- Revan's skin "began to boil and blister, the flesh of his face melting" as soon as the lightning got through his defenses. Vader, while mortally wounded as per many sources, nonetheless didn't look all that different from any of his other appearances without his helmet, indicating his wounds were less severe than Revan's despite the Emperor's lightning tearing all over his body "into his heart" and "penetrated his life-support and electrified Anakin's organic remains" according to The Rise and Fall of Darth Vader meaning that his lesser, subconscious Force barrier is stronger than Revan at his most stalwart.
- The Sith Emperor continued to "pour more and more power" into his lightning even after Revan's skin "began to boil and blister," insinuating that the Sith Emperor wasn't even at full strength when Revan fell under his might, as one obviously cannot add to something that is already at its zenith; the only way to do that would be under the conditions that the Sith Emperor wasn't giving it his all in the initial clash. Vader on the other hand experienced "the full force of his Dark Master's evil lightning" (link) whereas there is no indication whatsoever that the Sith Emperor went all-out on Revan.
It shall be noted that this version of Revan is more powerful than Jedi Civil War Revan.
This means, that Vader destroys Revan
