state of tanks in PvE?

title says it all

in retail warrior/brm monk were the best in HC SoO, with their defense (warrior) and avoidance (monk) and their high dps
paladin was top tier with their defense mitigation, healing and bubble
Next BDK with Super healing, magic defense and the ability of solo tanking bosses
last but not least, guardian druid: high defense value, high damage, raid healing and kiting ability

is there any non-viable (bugged skills/talents etc) tank spec in warmane?
are they working fine?

i played almost every tank on mop exept war and they are all good, u wont be having problem with any raid, just chose what u like.

I mained a Prot paladin in Retail MoP went 13/13 Mythic (Heroic as it was called in those days XD) And I can say that MoP had some of the most balanced tanking of any expansion I have played. Dks were SLIGHTLY behind in performance due to their spiky nature. But as AJDE said play which ever you feel the most fun playing.