What would they be? For me,
1. Single-player challenging content, like Mushin's Tower in Blade and Soul. Rewards could be anything from profession-only armor, to anything, really.
2. The Dragoon class, from Final Fantasy 14. I would just love to see that class as part of a pseudo-action combat MMO.
3. The ability to alter how our characters hold certain weapons, with a menu.
4. More mid-fantasy weapons. If you've seen the swords that Geralt uses in the Witcher 3, with runes and sigils, you'll understand my meaning.
5. A form of power progression that isn't strictly tied to your character's actual power. eg: The more you run, the faster and more often you can "Sprint".\
Any other ideas?