Self explanatory. Want to see which camp my Straight Dope Tolkien nerds fall into on this question. (stolen from http://http://www.tor.com/2017/05/09/smaug-vs-durins-bane-who-would-win-in-the-ultimate-dragonbalrog-showdown/?utm_source=exacttarget&utm_medium=newsletter&utm_term=tordotcom-tordotcomnewsletter&utm_content=na-readblog-blogpost&utm_campaign=tor )
Easy one–being a dragon, Smaug is the one with the wings.
Ninja’d, dammit!
The link doesn’t work either.
Smaug is much bigger, right? I’d put my money on him.
Here 's another try for that link http://www.tor.com/2017/05/09/smaug-vs-durins-bane-who-would-win-in-the-ultimate-dragonbalrog-showdown/?utm_source=exacttarget&utm_medium=newsletter&utm_term=tordotcom-tordotcomnewsletter&utm_content=na-readblog-blogpost&utm_campaign=tor
and yes, of course I meant to write “who wins?” not “who wings”
“As Iluvatar is my witness, I thought Balrogs could fly!”
Balrog is some kind of ancient demon thing from hell, right? Smaug is just a big mortal lizard with arrow proof scales, except for the tiny important area over its heart. Gandalf was OK with raiding Smaug’s lair, but at the first whiff of Balrog, he was all “Fly you fools!”.
So I’m thinking the Balrog is the scary one, if you’re on the Wizard scale level of power.
Gotta agree with Finagle.
Smaug was killed by a guy with a bow and arrow.
The Balrog took a Maia out with him.
In our first event, “slaughtering Dwarves and driving them from their home” they both get good marks, but I give the edge to the one who killed a Durin.
The Balrog, if he’s prepared.
I’m also going to say Balrog wins. No way you’re going to take it out with an arrow.
From the wiki, dragons were bred by Morgoth, the same one who seduced and corrupted the Maiar that became Balrogs. When breaking the siege of Angband, Morgoth used only a single wingless dragon, Glaurung, and a host of Balrogs. The History of Middle-Earth states the only thing more fearsome than a Balrog is a winged fire-drake.
Gandalf fought and killed a Balrog. He wouldn’t even attempt to fight Smaug.
Smaug is far larger, airborne, and most likely immune to fire. I just don’t see a Balrog, even one as noted as Durin’s Bane, having much of a chance in this one.
Peter Jackson’s bank account. 
Of the four named Children of Iluvatar that are known to have slain a dragon, three were mortal men and one was half-elven.
Of the three named Children of Iluvatar that are known to have slain a Balrog, two were High Elves and the other was Gandalf the Grey. None of these “survived” the encounter, either.
I suggest Balrog > Dragon, with the evidence we have.
It’s been a while, but wasn’t the Balrog on fire when it fought Gandalf (implying fireproofness)? If so, Smaug’s best weapon goes away.
Dragons have more physical power, but balrogs have more metaphysical power, and in a world like Tolkien’s, it’s the metaphysical that counts.
And those old-school High Elves were serious badasses. I mean, their king, Fingolfin, went the distance with Morgoth, and he was a fuckin’ Vala.
Balrogs are fire demons, so immune to Smaug’s breath.
I don’t disagree with the general assessment, but by that time, hadn’t Morgoth lost a lot of his raw power due to his activities in the areas of creating and animating creatures, and manifesting himself in physical form, and stuff like that?
I’m in the balrog wins camp. I see it like this: the dragon flies by, tries to burn (hah!) the balrog, who then snags a dragon’s leg with his whip and drags it down to the ground, where the balrog can destroy and disassemble the dragon at his leisure.
The answer is the Balrog wins by shooting a black arrow at Smaug’s hole, just like Bard did.