Free respec, on the fly without going to a trainer.
Area looting
No more mob tagging. Seriously, why? Competing for the same mob with 500 people is insane.
Built-in quest locations and map markers. No need for questie.
Customizable default UI. Let me move things.
Then once the QoL items, which exist in the retail client already anyway, are implemented you can start adding “new” instances, raids, etc.
How about this one?
https://i.imgur.com/hM2dsK2.jpeg