If we take them as pairs I think Kyle-Dark Kyle and Elhain-Dark Elhain are the best all around. The other two are a tie with Galek being too weak but Ultimate Galek being good and Athel being good but Dark Athel being too weak. IMO Galek should be buffed so Cursed Blade is an AOE that books up to a 70% debuff chance, it would be fine to lose the extra damage on his A3 for the additional chance to land his debuff. Dark Athel has a good kit she just needs to smack harder.

I personally  agree with Galek being buffed. 

Back in the day when I reached silver, I was getting smacked around by Dark Athel. But really gotta build her to nuke. 

Dark Elhain is really awesome and can't wait to try Dark Kael 

I really like Athel, I took her as starterchamp and she is still my campaign farmer for 12-3. But her dark counterpart never comes out of the vault. That champ doesn't feel like an epic, more like a mediocre rare.

Dark Athel's damagemultipliers are so low. I don't know why the developers create so many champs with insane base attack, just to give them an overall low damageoutput by small multipliers. Dark Athel is, in this context, the epic version of Bystophus. He has the highest base attack in the game and still doesn't deal damage due to low multipliers. Dark Athel has a very high base attack for an epic with 1465 (not the number one among epics, wich is probably Fayne), but Dark Athel still doesn't hit. 

I just don't get it. If they want to create attack champs that don't hit that hard like others, why do they give high attack with low multipliers? The multipliers are hidden in game, it just puts players on the wrong track. Champs with high attack should hit hard and the other way round. In reality, champs with low attack and high multipliers can hit insanly hard, and Bystophus (for legendaries) or Dark Athel (for epics) look like damage dealers from their attack stat, but hit like a wet noodle.

elhain-dark elhain. Ik dark kael strong, but dark elf to dark dark elf doesn't make sense to me. Other two are too weak.

Kael was my starter. For over two years of playing, I still have my Dark Athel at rank 4 level 40 lol. I Just 60 my Dark Elhain 

I maxed dark elhain for a arena nuker than pulled a skullcrown probably a week later. Dark elhain still carries me vs tormin teams though.