1. I wanted to have a game where your character starts off with a set amount of stats, skills, and weapon profs. Instead of leveling up, just add a more achievements that give boosts based on things that made sense.
2. Mess with Lords' stats. I often feel like the NPC lords are pretty useless on the battlefield, I would like to see them make more of an impact during the fighting.
3. Increase the amount of goods produced by villages, increase the item stack sizes/price. Basically boost up the trading aspect.
4. Along side number 3, make the goods production/consumption random based on area of the map. Really make every game different. Balance out the Enterprises.
5. Overhaul the autocalc (not sure if that's possible)
6. Improve AI (map and battle)
Plus a ton of other ideas, but these are the main ones I want to do.