Palpatine is considered the peak of the Sith because unlike the other Sith Lords, he seemed to have a functional brain and actually succeeded in pretty much completely wiping out the Jedi.
He used trickery to do so, and at the end of the day, he failed. Also, Palpatine was hardly the first Sith to nearly wipe out the Jedi.
Hell, the Sith during the Legacy Era EU even said something along the lines of ''We will not repeat Palpatine's mistake. All Jedi must die!''
That, and the Sith laugh at him for losing power too soon. To them, it doesn't make sense that he who only ruled for decades should command those who ruled for centuries.
The SWEU only seemed to know how to write pre- and post-Sidious Sith via boring-ass power level wankery. Not even going to get into the sheer retardation of how they tried to turn Revan, A CHARACTER WITH THE BARE MINIMUM OF BACKSTORY THAT IS QUITE LITERALLY JUST A CIPHER FOR THE REAL LIFE PLAYER TO OCCUPY, into some kind of actual character with retarded Gary Stu traits.
Except Revan annihilated the Mandalorians by using their tactics against them. Then later, he was running a successful war against the Jedi, convincing some to join him, corrupting them using the Mandalorian Wars to turn them to Sith, and then running Dark Jedi gulags that don't kill Jedi, but torture them and turn them into more Sith. Both Revan and Palpatine could've won if it wasn't for their traitorous apprentices, but Revan's Empire had more to offer thanks to them having more Dark Jedi.
Revan had the right idea Sith-wise with what to do with the Jedi. Order 66 was a colossal waste, when what Palpatine should've done, with his artificial control over both sides of the Clone Wars, was to corrupt the moral fiber of the Jedi, to prolong the war and make them see things from his point of view, and to isolate the Jedi Council and those Jedi who choose the Jedi Code over the Republic. So when Palpatine declares himself Emperor, he could get at least half the Jedi to defect alongside Anakin, and those Dark Jedi could help the Empire remain strong.
Imagine thousands of Dark Jedi serving the Empire and maintaining order and discipline among the Imperial ranks. The Rebels would stand no chance, especially since Dark Jedi are devastating in ground combat and are Newtype-level pilots in space combat. Hell, the idea was so good that the Empire tried to make Dark Jedi armies twice, and if it weren't for the quick-thinking and decisive actions of Kyle Katarn and Jaden Korr, the Empire would've regained their advantage and crushed the NR before the latter had time to spread its wings.
In terms of power, Revan and Sidious are probably equals. But in terms of strategy, tactics, and ideology, Revan has some edges over Palpatine, given that he was able to corrupt at least half the Jedi of his time, whereas Palpatine at most corrupted a handful, making his Empire fragile thanks to the lack of Dark Jedi/Sith leadership. Palpatine's one advantage over Revan was that he knew how to handle the politicians, and that's more due to his background and his experiences with Plagueis.
The problem with the Rule of Two Sith was that they were too fragile; you saw the movies-one paraplegic Jedi suddenly finding his balls destroyed them. Anakin vanquished Vader in his mind and then killed Palpatine with his hands. In a two-step move, the Sith went from ruling the galaxy to being extinct, whereas Revan's Sith were so durable that it took another Gary Stu Jedi to hunt them down and annihilate them. The Rule of Two Sith were annihilated by a paraplegic Jedi.