Group comp for Legion Mythic(+)

[Mercbeast]

I think your optimal group is going to be, warrior tank, + whatever healer you want to use, + 3 beast mastery hunters for mythic+.

Here is why. Warriors are far and away the best tanks right now. It's not even close. After that, we have Druids, then Prot paladins, then DH and Blook DK.

Blood DK and Veng DH are going to be very strong for your early mythic+ progression, to the point that they can literally solo bosses. However, as the difficulty ramps up, they fall behind.

The primary issue in Mythic+ is how fast can you clear trash. The two best AOE classes in the game currently (after Havok DH nerf) are WW monks and BM hunters. WW monks have the problem of being rather immobile for AOE and they are melee, so they get hit with cleave mechanics. BM have the advantage of complete mobility + battle rez + bloodlust + faceroll easy AOE damage.

This means that BM hunters will have no issues navigating mechanics, avoiding melee cleave damage, and putting out obscene aoe numbers while doing it. So if you're going for 3 chests and stuff like that, I'd probably run War+Druid Heals + 3 BM. You will slay aoe, have 3 aoe stuns, good mobility for dps and heals. A bear druid would also be useful for your tanking for the ability to share loot between heals and tank. So I would probably align my tank and healer in the same gear set.