And the winner is...
Mounted Combat!!! Yay...
Here is the full list of concepts that had multiple suggestions from pages 1-14. Grats to Hayoo on coming up with an original concept that a lot of people really want included.
Mounted combat: 29
Don’t know / change nothing / blank: 18
New hobbies / minigames: 18
Mentoring system (or similar): 13
Kinship / social related: 10
Other PVMP or PVP related: 9
Character customization: 8
World events / random events: 7
PVMP skirmishes: 7
Hayoo’s ideas (tavern revelies): 6
Collision mechanics: 6
Instance / raid scaling: 5
Housing / storage related: 5
Crafting related: 5
Mount customization: 5
UI related: 5
Cross server instancing: 4
Combat system overhaul: 3
Player created quests/content: 3
Itemization related: 2
Graphics fixes: 2
Session play: 2
BOA changes: 2
Oh and a further bit about mounted combat... It has been suggested that linking Rohan with with an expectation of mounted combat inclusion is a logical fallacy. The only thing I can reference in reply is the meaning of the word: Rohan means "land of the horse lords" in Sindarin.