Dragons vs. Balrogs?

[Maédhros]

Actually there is a quote from The Book of Lost Tales II: Turambar and the Foalókë

Now those drakes and worms are the evillest creatures that Melko has made, and the most uncouth, yet of all are they themost powerful, save it be the Balrogs only.

The Tale of Turambar and the Foalóke was written circa 1917, before the Tale of Tinuviel. If we couple that with the fact that Tolkien drastically reduced the number of Total Balrogs in existence from Hundreds in the The Fall of Gondolin to at it's most only seven, so as to make them stronger and deadlier if you will.
It appears that Balrogs are indeed more powerful than Dragons.
On the other hand, it could be said that, at that time, Winged dragons didn't exist and you could make the argument that the quote doesn't apply to them.