Best UU per Era

What do people think is the best UU in each era?

(Except the Modern because there is only Foreign Legion and Future which has none.)

Ancient Era - Hoplite (can match swordsmen in most player-controlled scenarios and doesn't need iron)
- Atlatlist (can get it earlier and cheaper)


Classical Era - Mohawk (can be spammed for no iron and can cancel out forest defence bonuses)


Medieval Era - Longbowmen* (promotion is better for Gatlings and Machine Guns than CKN)


Renaissance Era - Minuteman (super-scouts)


Industrial Era - Carolean (what's not to like about the March promotion?)


Atomic Era - B17 (they become Stealth Bombers)


*Medieval Era disregards Keshiks and Khans don't really fit. Poor Genghis.

What are your favourites/most useful UUs for each era? Please leave opinions. ;)