I am playing tank, so this is opinion from tank point of view.
Something I noticed that when doing high level m+ most affixes mostly punish tank and healer. Tactic for almost all trash is stun until diminishing return kicks in and then kite and as tank kiting feel really unrewarding when you don't actually get to use your skill but just run around mobs.
Here is tactic for affixes:
Necrotic - tank kite until stacks drop out
Bolstering - kill mobs same time, but if dps fail then it's up to tank to kite. This doesn't punish dps for failing but tank.
Raging - use stuns at 30% hp but if someone used stuns before and mobs got diminishing return on stun then its tank who kite again.
Sanguine - tank kite mobs out of red stuff (also make sure you move mobs far enough from red stuff so that melee dps move out from it too)
Skittish - tank spam taunt
Teeming - more incoming damage to tank and more dps fodder for dps
Volcanic - move out of yellow stuff. This mostly effect range dps/healer, but is far more punishing for healers.
Overflowing - Just effect healers and more holy paladins than other healers.
Fortified - Mostly just kite depending what other 2 affixes you got before.
Tyrannical - This best affix in my opinion and how mythic dungeon bosses should be. Bosses feels trivial compared to trash outside this affix, which is shame since there is lot more variety to bosses than there is to trash which play almost same everywhere (stun/kite).
I feel like m+ could have been lot more interesting if focus was on bosses more and less on trash.