I heavily agree with Cragstone. Just wanted to add that in order to fix the issue where you can feel tanky vs solo mobs but not elites, flat mitigation could just have different values against elites. Keep it where it is for solo mobs, then have it doubled (or whatever number) against elites. Also part of it is just that death doesn't mean much outside of full wipes or playing hardcore/fairy. Revives are cheap, especially with tether and it's normally easy to run back anyway.

Cow is not meta however, it has great taunt, but only flat physical mitigation basically, which is ok for gk, but the moment you get to wintertide you get absolutely destroyed by the cold, fire and darkness damage there. Unarmed is the only tanking skill which provides enough % mitigation from darkness, physical, etc. although it has holes in its elemental defence (as it should). You can't use shield as a cow as well, which is normally the skill used for elemental defence because of elemental ward. It is incredibly cooldown based though, just like staff and there isn't really a good skill in the game for elemental defence at all. What ends up happening is you get the % mitigation from items such as old crusty's shield, hunter's breastplate etc. and meditations. You can also build evasion, but you still need mitigation to go with it because of rng, and the moment you get stunned you're dead because being stunned disables evasion.