Ancalagon the black would a better candidate, and here's why. He's huge. He makes Smaug look like a chihuahua. Google him if the link doesn't work. https://www.google.com/search?site=&source=hp&ei=XbaaVYHwCsn5-AGtyLXwCw&q=ancalagon+the+black&oq=ancalagon&gs_l=mobile-gws-hp.1.0.0l5.159.38004.0.39718.104.22.168.22.214.171.1243.2063.0j5j2j1j1.9.0....0...1c.1j4.64.mobile-gws-hp..1.9.1444.0.QoagwQiNsVE#imgrc=FHd-UY1KVHeyGM%3A
It took an entire host (doesn't give an exact number) of elves and eagles to takw this guy down. When he died, he fell, and destroyed and entire mountain range. He could hold a volcano in his palm. This dragon was also said to have fathered all of the winged-drakes. He was the greatest winged dragon that Morgoth, the big bad from the first age, controlled. If that's not enough to convince you, then please remember, he destroyed an entire mountain range of some of the largest mountains when he was killed .