Both Morgoth and Sauron managed to inflict significant damage upon the world and their enemies before their downfall, but Morgoth was undoubtedly the more powerful of the two.
In the depths of time, Eru Ilúvatar created Arda and the Valar. He made the Valar to help create and order the world, but the most powerful Valar, Melkor, turned out to be nothing but problems.
Defeated by the Host of Valinor in the War of Wrath, Morgoth was banished from Middle-earth into the Timeless Void, though it was prophesied that he would one day return.
However, the mere fact that the Valar didn't prioritize perusing Sauron proved he was a much lesser threat than Morgoth. It made perfect sense because Morgoth was a Valar, and Sauron was only a Maia. So, while Sauron was evil, Morgoth was clearly much worse.
This is really a pretty easy question. The answer is, by far, Melkor. Melkor, or Morgoth, wanted to currupt and destroy everything good created by the other Valar. Sauron on the other hand only wanted to control and rule Middle Earth.
Finally Sauron came out to fight Elendil and Gil-galad face to face. When Elendil fell, his sword Narsil broke beneath him. Isildur took up the hilt-shard of Narsil and cut the One Ring from Sauron's hand, vanquishing Sauron.
Additionally, while he was in his weakened state, Galadriel could hold him off through the power of will alone. However, if Sauron had his One Ring and faced off in a battle against Galadriel, it's unlikely that there would be much she could do.
He is described as being equal in power to Manwë, chief of the Valar in Arda. But his power increases in later revisions of the story until he becomes the most powerful among them, and in a late essay more powerful than all of the other Valar combined.
Ultimately, the only being more powerful than Morgoth in his prime was Eru Ilúvatar. Only the combined effort of the Valar could stop Morgoth, and only after countless battles. Sauron might have bested his mentor under certain circumstances, but Morgoth is the greater Dark Lord by every metric.
However, near the end, Morgoth had dispersed so much of his own power into the world, that (Tolkien wrote in a private letter) he was actually weaker than Sauron. Sauron made torture a specialty. Morgoth tortured people too, but Sauron was really into it.
She had no role in the major wars of the First Age, believing that defeating Morgoth was beyond the power of the Eldar; when Morgoth was defeated by the coming of the Valar out of the West she, having played no part in the earlier Kinslaying, was offered safe return to Valinor.
Gandalf pursued the monster for eight days, until they climbed to the peak of Zirakzigil, where the Balrog was forced to turn and fight, its body erupting into new flame. Here they fought for two days and nights. In the end, the Balrog was defeated and cast down, breaking the mountainside where it fell "in ruin".
For that matter, the Valar didn't have the authority to remove another Ainur's power. If they had had that authority, they would have stripped Morgoth of his power, rather than going to war with him so many times.
"So I think in his pitch to Galadriel, it cannot mean that he loves her or that there's any kind of romantic relationship. There should be no ambiguity around the fact that Sauron is evil — he's terrible, and he's using Galadriel to enhance his power."
It was said that Morgoth hated and feared the House of Fingolfin the most of the three Houses of the sons of Finwe, and he feared most Fingolfin's son Turgon, as it was prophesised that from the House of Turgon would his doom come.
Characters who can easily defeat Sauron are; his Creator Eru Ilúvatar, his old master Melkor, and the Valar. Others who could overcome him would be Ungoliant who physically dwarfed Morgoth, and some great Maiar of Valinor described as almost as great in power as the Valar themselves.
Secondly, Balrogs were the epitome of malice and power while Sauron only ever won one of three fights he ever had. Sauron was the great deceiver. His power lies in planning, subterfuge, manipulation, and corruption.
Envy: He hates how he cannot make life and is jealous of Eru's ability to create life which is why he creates Discord and is the prime motivation of Morgoth. If it isn't mine, then I will destroy it. Gluttony: He breaks his promise and betrays Ungoliant, so he can keep the Silmarils for himself.
As they did when the elves were first born, the Valar came to Middle-earth and defeated their brother, but this time Morgoth was cast into a void outside of existence, where he remains thereafter.
While not appearing in the film series (most likely because he no longer existed in the world at the time of the said series because of his banishment to the Void in the War of Wrath in The Silmarillion), Morgoth's most powerful servants, such as Sauron, still thrive, and Morgoth was mentioned in The Lord of the Rings ...
In his notes, Tolkien remarks that Sauron saw Galadriel as his equal. Add that to the fact that she's untrusting of Sauron (yes, even when he's in his Annatar guise) and an unwavering, single-minded force, and it's more likely than not that Sauron feared Galadriel — or the potential she held to upend his plans.
Though neither is someone you'd wish to annoy, Galadriel is generally considered more powerful than Elrond in Lord of the Rings. Not only is she older than her Rivendell counterpart, but Galadriel witnessed the light from Valinor's Two Trees, giving her a mystic quality.
