As a Horde main, there's one thing in particular that I'm looking forward to in Shadowlands.
NO MORE DAZAR'ALOR. It's a beautiful looking place, but good lord things are too spread out between the temple and the docks. I made the mistake of leveling an Alliance character and exposing myself to the sweet, sweet compactness of Boralus so I know exactly what we're missing out on as Horde.
