For me it was the Dance Studio.
I've been pretty blatant about my dislike for Azerite Armor this expansion, to the point where I worry at times that I'm too hard on it.
Now that Legion is basically in the can, it's time we can sit back and look over the past couple of years and think about what we liked best about it.
Warlords had the garrison, Legion had the Order Hall and the Artifacts.
With all the discussion and debate among the community about the removal of flight from future World of Warcraft content, it occurs to me that this also marks an opportunity for us to reflect on features that have been introduced to the game over the course of various expansions.