My vote goes to the Balrogs
The Balrogs were maiar, spirits of fire, they came from outside Arda and were of the same kindred as Morgoth or the Valar. Only Sauron among Morgoth's servants was more powerful.
Remember that Gandalf did kill the Balrog but it costed him his own life, and remember that Gandalf was himself a maia, and that Balrog wasn't Gothmog, they lord and more powerful Balrog.
Smaug, the most powerful dragon in the third age was killed by a single arrow, shot by a man, I doubt you would kill a balrog that easily.
Dragons were creatures created by Morgoth, what was their exact nature? it's not explained. As the werewolves, they might be evil spirits that adopted those forms, so, they could have been ainur (maiar in Arda) but i believe that even if that was the case, they were spirits less powerful than the Balrogs.
Remember the Balrogs were able to even defeat Ungoliant, I think Ungoliant would have eaten the dragons as appetizers.
|