Gothmog, one of the first Balrogs to become Morgoth's allies in the First Age, is regarded as the most powerful Balrog in Middle-earth. As the High Captain of Angband, he is given the title 'Lord of Balrogs'. Although he carries a fiery whip to battle just like the rest, he is also renowned for having a large black ax.
The Elf Ecthelion leads the charge against the Orcs, and fights Gothmog, the greatest Balrog; they wound each other and both fall into the king's fountain in Gondolin; both drown.
Ranking the 9 Powerful Monsters of Morgoth - LOTR Lore
Was Sauron afraid of the Balrog?
Sauron does not fear Durin's Bane because essentially they had been allies back “in the olden days". Both Balrogs (all balrogs) and Sauron chose to serve Melkor/Morgoth.
Gandalf the Grey was able to defeat the Balrog (granted, at the cost of his physical form), so the end result would likely be the same for the significantly more powerful Gandalf the White.
There is no account of any dwarf ever killing a Balrog, let alone multiple. The only recorded instances of Balrogs having been slain are Gandalf's slay of Durin's Bane, Echtelion's slay of Gothmog and Glorfindel's slay of an unnamed Balrog.
Gothmog, one of the first Balrogs to become Morgoth's allies in the First Age, is regarded as the most powerful Balrog in Middle-earth. As the High Captain of Angband, he is given the title 'Lord of Balrogs'. Although he carries a fiery whip to battle just like the rest, he is also renowned for having a large black ax.
Still, the dragons proved more effective in battle. Then there's Gandalf the Grey, who managed to kill a Balrog single-handed, but decided to manipulate some Dwarves and one very reluctant hobbit into dealing with Smaug.
Casualties. The Battle of the Peak was the climax of the fight between Gandalf the Grey and the Balrog Durin's Bane atop Zirakzigil after they ascended the Endless Stair from the depths of Moria.
After sleeping deep within the Misty Mountains for thousands of years, he was awoken by the Dwarves of Moria in the Third Age, responsible for the death of King Durin VI and the ruin of Moria; it was the Balrog encountered by the Fellowship of the Ring.
Glorfindel fought the Balrog and succeeded in slaying the monster, but was himself mortally wounded. His body was recovered by the great eagle Thorondor and buried under a stone cairn, where afterward grew yellow flowers.
The Balrogs were Maiar corrupted by Morgoth during the creation of Arda, who cloaked themselves in shadow and flame and carried whips and swords. Famed Balrogs include Gothmog, slain by Ecthelion, and Durin's Bane, slain by Gandalf.
After disinheriting his son, King Durin banished Elrond and ordered the new mine to be sealed up, but not before he cast a leaf from the tree in Lindon into the mine, where it floated down and awoke a Balrog that had been lying dormant beneath the mountain.
In all of Tolkien's text I've read, there are three people who have killed a Balrog. Ecthellion, Glorfindel and of course Gandalf. All of these fights ended in a draw with all three sacrificing their lives for the deed.
It can be traced to a footnote Christopher included attached to his commentary quoted above from the Second Book of Lost Tales; "* The idea that Morgoth disposed of a 'host' of Balrogs endured long, but in a late note my father said that only very few ever existed - 'at most seven'."
6 Gandalf. As previously stated, Gandalf is a Maia and is therefore superior to Elves regarding power. Still, this isn't to say that an elf couldn't develop enough skill and power to defeat a Maia. As a bearer of one of the Three Elven Rings (Nenya), Galadriel would have an edge against Maiar like Saruman and Radagast.
Thus, Galadriel's dark form in Jackson's The Lord of the Rings personified what would have occurred had the Lady of Lothlorien given in to temptation and taken the One Ring for herself. She would have succumbed to evil because the Ring was indomitable, even with her power.
But it is doubtful that Sauron (without the One Ring) could have commanded the Balrog to say attack Lorien or fight against Minas Tirith. The main powers of a Balrog are not against armies of lesser enemies, or in breaking castle walls, but rather against other powerful opponents like Wizards or Elf-lords.
Balrog vs dragon, as a general setup, is simple to answer. Balrog. Even in the earliest writings, when Balrogs were much, much weaker and more numerous than they are in the conceptions you probably identify with them (as in, what Gandalf fights), Balrogs are stated outright to be more powerful than dragons.
