Drogoth the Dragon Lord
Drogoth, who is named the Dragon Lord because of his likeness to the great Dragons of old, is one of many dragons that originate from the Withered Heath in the Grey Mountains in the far north of Middle-earth, and is one of the few who still seeks power openly. Before the War of the Ring, Drogoth slept undisturbed. But he was persuaded by Sauron to help in his campaign in exchange for one of the Dwarven Rings of Power which were confiscated from the heads of the seven major Dwarven clans when they were captured and held in Dol Guldur.
Drogoth flew to the Blue Mountains and drove out the native Dwarven clan, and turned it into his new lair. The survivors sent a lone messenger to get help. This messenger made his way east and was captured at the Ettenmoors by the Goblins. He is later rescued by an Elven army under Glorfindel and Glóin and tells them what has happened. The heroes set out for the Blue Mountains and with the help of a small Dwarven army made up of the survivors of Drogoth's devastation, they retake the mountain halls, drive out the Goblins that have infested them, and kill Drogoth. The Dwarven ring is recovered and the Blue Mountains reclaimed.
So I was wondering how would you rank Drogoth compared to other dragons like Glaurung, Ancalagon, Scatha, and Smaug and also compared to the balrogs like Gothmog.