Hearthpwn

I like the tribe and the game play, but honestly they are indeed too powerful and it's crazy. Elementals could still be beaten by either Divine Dragons or Poisonous murloks in their time. Even dragons had competition with murloks back in their hay day and were notable for being one of the only tribes able to counter Divine Poisonous Murloks. Barron Beasts was also a really strong build, as well as Exodia Pirates, though they took some luck and fineness to work out. 

Quillboars are much stronger than anything we have ever had before. Their ability to scale is far greater than any other tribe and on top of that they offer cards that have synergies with all minions, powerful ones to boot. Not only that but a lot of their powerful scaling minions are on 3 which is way too early. 

Barron Beasts with Golden Barron, Golden Macaw, Golden Goldrin, and Hydras or even Myexna : Not enough, Saw multiple streamers get this dream build and they couldn't compete with 100/100+ Quilboars. 

Poisonous Murloks: Not enough to win if the enemy has scaled Divine Quillboars, only George could maybe do it if he isn't the one playing Quills and even then a single Ghoul is enough

Dragons: Too slow to scale if you are even lucky enough to find a Kalecgos.   

Elementals: The only other viable choice with Tempest if you don't get out scaled by Quills which is hard. You would need a golden Nomi and even then it would still be very difficult.

Pirates: Not even close

Demons: Still a solid top 4 if you're interested in MMR gains, but then that's like going to a red lobster just to eat fried chicken. 

Mechs: Scrap metal

they're just way too good early game and share the same space Mega Saur had. if you don't get Quill or beat them before they hit 5/6 tier, you will inevitably lose.