@Tyrri WHOAH ! Hold your horses mate !
Parry tanks are in excellent state both for M+ and raids. Yes, they are more gear depended than crimson/bear (e.g. bear can brainlessly equip higher ilvl, parry tank needs stat priority) but their stagger mechanics make them "immue" to burst and so much easier to keep alive - personally as a healer main they are my favourite kind of tanks.
Bear tanks are shit in 90% encounters beacuse of how much damage they take. Yes, they have giant HP pool and good damage output but keeping them alive (specially during Grevious wounds week) is pain in the ass. In their defence i have to say - they shine in every situation that a tank is getting stunned/disabled beacuse being stunned makes parry/crimson tanks unable to parry/block/dodge - they start taking as much damage as bears.. but again - bears have 2x more HP so they easily deal with stuns.
Mana tanks scale with gear, this is all you have to know. The better the gear, the easier content becomes for them. At start of TBC manatanks were absolute trash, now they are definitely playable. A week ago i did M9 with my manaforged friend that has 126 ilvl (but already optimized ~half of his gear). Nothing too crazy but to be honest - i have feeling that 130ilvl with fully optimized gear he will be comparable to Crimson and should be able to beat him later on.