Ranking Unique Units on their Importance to their Civilization

Please note, this list is my personal opinion and based on only one factor: how much would a civilization suffer if if did not have that unique unit available. This isn't a list comparing unique units head to head. Feel free to give your own suggestions/ranking. Secondary units such as eagle warriors and condottieri aren't considered for this list.

1 Plumed Archer

2 Longbowman

3 Huskarl

4 Chu Ko Nu

5 Janissary

6 Kamayuk

7 Conquistador

8 Rattan Archer

9 Mangudai

10 Cataphract

11 Genoese Crossbowman

12 Camel Archer

13 Boyar

14 War Wagon

15 Organ Gun

16 Magyar Huszar

17 Mameluke

18 Berserk

19 Jaguar Warrior

20 Arambai

21 Woad Raider

22 Elephant Archer

23 Shotel Warrior

24 Teutonic Knight

25 Karambit Warrior

26 Samurai

27 Gbeto

28 Ballista Elephant

29 War Elephant

30 Throwing Axeman

31 Tarkan