Warehouse, granary, bakery, flour mill, resource multipliers (saw mill, etc.) _________________________________________________________________________________________________________
I disagree with the above answer. It depends on what you want to do. If you want to farm someone, you have 2 options.
Option 1: take out the main building, barracks, stable and rally point
Option 2: take out all wheat fields, main building, granary, flour mill and bakery.
If you just want to hurt them, take out the main building, warehouse, granary and then take out all wheat fields, their grain mill and bakery.