Who is more powerful?

[Smelt]

Sauron vs Gandalf.I think that Sauron is by far the most powerful maia , seeing that Gandalf feared Sauron in the movie!

[Khadrane]

Definitely Sauron. What about Radagast, Saruman (before he turned evil) and Gandalf versus Sauron? Who'd win then?

[markedel]

All 3? Perhaps but the Istari could not reveal themselves fully without turning bad.

[Andúril]

Smelt, how do you define powerful?

[Lightice]

Sauron was most powerful of all maiar, as Melkor was most powerful of all Airur.
And Istari weren't allowed to straightly attack Sauron themselves, but they had to encourage the Free Peoples to do it. This was to prevent corruption, which unfortunately took place in Saruman.

[Smelt]

When I say powerful , I am describing physically how strong in magic or brawn .And in my mind Sauron was the most powerful in both attributes.Also no mair can withstand Saurons ring as they will turn evil.

[Smelt]

Originally posted by Anduril
Smelt, how do you define powerful?

I define powerful as strength in combat, or magic and I think that Sauron was physically more powerful, and there is no doubt that Sauron would beat Gandalf in a one on one confrontation.Just remember that none of the mair can withstand the power of the one ring successfully and that is a testament to Saurons power

[Andúril]

Sauron was most powerful of all maiar, as Melkor was most powerful of all Airur.

Just because Melkor was the most powerful in his beginning, that does not necessarily make his followers the most powerful by default. And if you think it does, then how powerful was Sauron when Morgoth had dispersed the majority of his power? He was only the most powerful for a while.

Smelt:

When I say powerful , I am describing physically how strong in magic or brawn .And in my mind Sauron was the most powerful in both attributes.Also no mair can withstand Saurons ring as they will turn evil.

I define powerful as strength in combat, or magic...

If the matchup was between Olorin and Sauron, the answer to your question would be much more difficult to come by. However, naming Gandalf specifically implies Olorin in his Istar form.

Gandalf, as everyone knows, was sent by the Valar with the Istari to rally the free-peoples of Middle-earth against the threat of Sauron. They were not allowed to show their true power, for a number of reasons, one being that if they had the ability to exhibit their full power and authority, and they would become the new dark lords of Middle-earth (after overcoming Sauron).

What did this restriction imply? Clothed in a humanesque body, they became subject to physical limitations and emotional interference (clouding judgement, etc). You would often read about Gandalf in LOTR as being bent over his staff like an old, frail man. That was Gandalf the Grey, second in appointed authority among the Isatri. When Gandalf became the White, these restrictions were lessened, but not by much. If you cast your mind back to the Weathertop scene, lightning bolts were seen from afar by the fellowship - this was Gandalf in combat with the Nazgul. Later on he is seen with his lightning bolts at the Pellenor fields - there doesn't seem to be too much of a power advantage. It seems that his body now effects him less in terms of psychological or emotional interference, as he is now able to handle those of some authority with ease when in the verbal confrontation.

When the balrog of Moria confronted Gandalf, we see a being of similar stature - another maia. However, this maia did not seem to have any of these purposeful limitations set on it - in fact, while it served Morgoth during his time in Arda, these balrogs received "power-ups" from their lord (similar to Carcharoth). It is very hard to come to the conclusion that any maiar who followed Morgoth went through life with their native power unenhanced. But that is besides the point.

Even in this lob-sided confrontation, Gandalf is widely believed to have proven victorious, dieing from mortal wounds after shoving the balrog off the mountain. It seems that historically, balrogs tend to die from a fall - this however does not show that they were weaker than their opponents. Look at Ecthelion.

When referring to Sauron, we must remember that his power fluctauted continually. He become very powerful, then died, then built his power up again, then died again, and then built his power up again....

From this, it is difficult to determine Sauron's power unless a timespan is given. After all, would we ever put Sauron in a fight against Olorin, straight after his body had been killed in the War of the Last Alliance? No. Therefore, I think that you need to stipulate at which point in their lives respectively, each opponent was during the combat.

Another thing to ponder, is the fact that power does not imply combat. Take Luthien for example:

But suddenly some power, descended from of old from divine race, possessed Luthien, and casting back her foul raiment she stood forth, small before the might of Carcharoth, but radiant and terrible. Lifting up her hand she commanded him to sleep, saying: `O woe-begotten spirit, fall now into dark oblivion, and forget for a while the dreadful doom of life.' And Carcharoth was felled, as though lightning had smitten him.

Here we find a being who had a maia for a mother, and the king of the Teleri, Elwe, similar in stature to Finwe and Ingwe, the High-King of the Eldalie, as a father.

Later she sings a song to Morgoth himself, who as a result, falls off his throne, and finds himself in a dream as dark as the Outer Void.

What am I trying to show with this? If two beings came together to contest their power, it would not necessarily be in terms of combat. Look at Finrod and Sauron's duel of song, for instance.

[Lightice]

Just because Melkor was the most powerful in his beginning, that does not necessarily make his followers the most powerful by default. And if you think it does, then how powerful was Sauron when Morgoth had dispersed the majority of his power? He was only the most powerful for a while.

Melkor was the most powerful all the time, but he didn't have any allies of greater strength, so he had to spread his own power amongst his minions.
And Sauron's power after Morgoth's fall was his own. However, he was foolish enough to bind most of his power to One Ring, thus creating a deathtrap for himself.

[Andúril]

Melkor was the most powerful all the time

Is that why he was afraid of Ungoliant? And what about Luthien? Or Tulkas?

...so he had to spread his own power amongst his minions.

...thus diminishing his own power.

And Sauron's power after Morgoth's fall was his own.

How can you be so certain. If I had my Silmarillian with me right now I would quote a passage showing how Morgoth used to transmute his spiritual power amongst his servants - that on its own is enough reason to expect that Sauron too had his native power increased - although this is speculation.

My point is, though, that Sauron's allegiance with Morgoth does not imply that Sauron was the most powerful maia. We must look elsewhere if we are to find mention of that...

[barrelrider110]

Much of Sauron’s “power” at the time of the war of the Ring was vicarious—he seduced Saruman and the free people of the East and South to join him and his Ringwraiths and army of Orcs. Likewise, Saruman built an army and persuaded others to do his dirty work for him. Leaders derive their power from those who follow them. This theme is clearly evident throughout Tolkien’s writings. Tolkien had first-hand experience the wars of the early part of this century. The world leaders that started them—Bismarck, Hitler, Mussolini, and Tojo-- derived their power from those they seduced. Even though Gandalf, Sauron (sans ring), and Saruman were powerful conjurers, the source of their true power was the willingness of their followers to do their bidding.
As Anduril stated:

Gandalf, as everyone knows, was sent by the Valar with the Istari to rally the free-peoples of Middle-earth against the threat of Sauron.

Anduril also points out that the Istari were forbidden to confront Sauron directly which makes the question moot but since this is all in fun an opinion couldn’t hurt.
I believe that Gandalf the White, just as he cast down Saruman, could have done the same to Sauron at the time of the war of the ring. Gandalf the White was more powerful than Gandalf the Grey. Once Saruman was stripped of his army Gandalf defeated him easily in the re-match at Orthanc. As for Sauron, even Aragorn had a brief contest of wills in the Palantir. Without his ring and his followers, I think Gandalf would easily have beaten Sauron.