1 Darth Sidious There has been no Sith, as powerful, meticulous, nor as evil as the Emperor himself, Darth Sidious. As previously mentioned, Sidious trained in the Dark Side by Darth Plagueis before Sidious killed Plagueis in his sleep, making Sidious a Sith Master.
So, a Gray Jedi typically has the superior immediate strength of a Sith, maybe with less chance of “burning out,” to put it lightly (or burning up, in Anakin's case). However, they still don't fully come to the full, long-term victory of the light side.
However, minor elements of Sidious' character betray the extent of his power, and it's hinted that in the end, it was his underestimation of his Master that led to Palpatine's death in Star Wars, which means that perhaps Plagueis truly was more powerful all along.
As the first Dark Lord of the Sith, Ajunta Pall founded the first Sith Empire and expanded it onto other worlds. The Sith took over the planet Ziost and created it as their capital and as Pall's new home. Pall eventually died after serving the Empire for many decades, but his Empire lived on.
According to Star Wars Legends content, the first Sith was a former Jedi Master, Ajunta Pall, who became a so-called Dark Jedi, or “Fallen” Jedi.
Emperor Vitiate was a Sith Lord who successfully gained near immortality by draining the life force of an entire planet, later attempting to drain all life in the galaxy, which would give him true immortality.
Yoda will most likely win in a fight against Darth Vader because he is more skilled with a lightsaber and has the experience and feats that allow him to trim whatever size and strength advantage Darth Vader has over him. In fact, Yoda nearly defeated Palpatine, something that Vader could never do.
Few Sith were as haunting and terrifying as Darth Nihilus, a Sith Lord who was almost an apparition, rather than a man. He barely spoke, preferring instead to communicate through the Force, which made him almost impossible to reason with.
Weaker - Anakin Skywalker
Anakin could have surpassed all Jedi in power, but instead was seduced down a dark path before he could do this. Despite how close he was to doing so, Anakin never reached the power of Yoda, and it is as simple as that.
Jedi like Luke Skywalker and Obi-Wan Kenobi have long stood as light against the darkness. But the record Sith-killer is actually Darth Bane himself. Darth Bane, founder of the Rule of Two, killed more Sith than any Jedi in the history of the Star Wars galaxy.
Even though Kylo Ren uses a red lightsaber, harnesses the dark side of the Force, and wears a cape, he is not a Sith. Because of that, he can never hold the title of Darth. Instead, he was just a chaotic mess of the dark side (until he eventually found his way back to the light).
Of all the Sith Lords before and after, none are more treacherous, dangerous, and evil than Darth Sidious. Not only should he be on this list of evil Star Wars villains, he practically created the need for it.
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%.
Within the Star Wars Legends continuity, Yoda's Jedi instructor was N'Kata Del Gormo, a Hysalrian Jedi Master, according to an in-universe legend.
In Star Wars Legends and Canon, Galen Marek (Starkiller) is the only Jedi (other than Obi-Wan Kenobi) to put a beat down on Darth Vader/Anakin Skywalker.
A Sith Lord with the ability to cheat death and create life, Plagueis is the mentor of Sheev Palpatine / Darth Sidious, who, in accordance to the Sith's Rule of Two, eventually betrays Plagueis by murdering him in his sleep, taking his place as Sith Master.
If it came to strategic prowess then most likely you'd find Sidious ahead. He was the one after all who managed to outsmart the entirety of the Jedi Order and Republic (minus the few individuals aiding him). And was then smart enough to keep any rivals in line or at a distance during his reign as emperor.
Sidious used Plagueis' methods to transfer his consciousness to a new body after his first demise. During the Battle of Endor in 4 ABY, Sidious was killed by a redeemed Anakin Skywalker, who turned back to the light side of the Force and threw Sidious down a reactor shaft to save his son Luke Skywalker.
This ensured that the Sith could hone their skills in secret without fear of betrayal from rival Sith factions. More cunning and devious than all but the most attuned Force-sensitive beings, Darth Bane could more than likely defeat Yoda in a battle of both strength and wit.
Yoda was tempted by the dark side on a few occasions throughout his life. If he fell to the Sith ways, he would've been more powerful than Palpatine.
Eventually, Sion was struck down, but he did not die. Instead, the pain within him welled up to agonizing levels, driving Sion to rise once more and strike down his would-be killer with all his anger and hate. Sion found that he could hold his own decomposing body together with the dark side of the Force.
Palpatine tells Anakin of the legend of Darth Plagueis, a Sith Lord who was said to be so powerful he could both create life and prevent people from dying. Anakin is very receptive to the myth, as nightmares of Padme's death have haunted him relentlessly.
Darth Shain, headmaster of the Korriban Temple, took notice and convened with the Dark Councilor and Dark Lord of the Sith Darth Shane McMahon, who decided to confer the title of Sith Lord to the young apprentice at the age of 11, making him the youngest Sith Lord in the history of the Sith.