Gunbreaker
But in all seriousness
From a PvP perspective, there are only 2 real tanks in the arena setting and thats Guardian druids and Blood Death Knights.
Guardian druids can dish out tons of aoe damage and just never die, so their in the center of all the fights .
Blood Death Knights don’t dish out as much damage as the Guardian druid, or can mitigate and heal as much as the Guardian druid in pvp the Blood DK’s job in arena is to basically keep the healer pinned down behind a pillar with death grip, chains of ice, and other crowd control abilities they have. They are meant to disrupt and to break the unity of a team more so than just soaking / dishing out damage.
In terms of world content Warriors, Brewmaster Monks, and Vengenace DH’s are quite slow and can feel boring. Protection Paladins and Guardian Druids can dish out great damage and survive pretty anything the world content throws at them with the exeception of world bosses.
In terms of dungeons all tank jobs perform well with Guardian druids being at peak performance.
I would say the top 3 tanks just for general gameplay ranked is: Guardian Druid > Blood Death Knight > Protection Paladin = Protection Warrior > Vengeance Demon Hunter > Brewmaster Monk.
As you noticed and commented about the lack of brewmaster monks. The spec is not performing well outside the raiding scene compared to its other competitors. It is viable in all content, its just that every other tank in game pretty much beats them outside raiding.
I love Guardian druid and they have 2 nice builds for pve. The moon bear and the blood bear. Moonbear specializes in magic damage through moonfire as well as a new ability they get for going Moon bear. While Blood bear forsakes its magic path and fortifies / buckles down on its basics of bleeds.
The moonbear is great at raiding and does well for dungeons while the Blood Bear is actually considered the best tank for mythic plus due to its insane rage regeneration from bleeding tick damage that gives them more rage. So you could pull 3-5 mob backs and actually tank that.
Most people consider guardian druid boring, but i find it fun and simple 