The final map feels like it has some insanely good drop rates compared to the others. Almost every run has been 5 units. I ran a calculation back when i assumed the drop rates were the same and 40cha came out better at gold and prince exp but lost to the 30cha map in unit exp. If this is not just an insane luck streak for me, however, then the 40cha map is better since you get drops more often.