What is the most valuable Strategic Resource?

[Blademun]

Banana First again

Personally I would have voted for Cucumbers first, they are much more fun..and you can sing about them on long car trips. However, bananas have several songs about them, more then any fruit. Though more is not always better.

However, important as Bananas and Cucumbers are...we cannot forget the Yaks. They are required to build many great things. What would all this..iron..and coal..and oil..be..if there were not Yaks! What would we break are earliest farms soil with? What would drag the great rails of iron in place? What, oh dear lord, would we feed our families without their milk..My god, to think you all could forsake them! Why, civilization itself stands upon the hairy, smelly back of the Yak!

Yessir.

[Cerbykins]

Wouldn't worry about saltpeter, it alone does not normally make or break a game
(unless it's close running to that point and you NEED to win a war mid-game...)
As for horses, their loss only usually hurts in either the absence of iron (and vice versa! ), and in horse specific strats like use of the Iroquois UU, the upgrade from zillions of chariots to their UU, and so on

[Arnelos]

Iron or Coal, Iron or Coal, Iron or Coal....

IRON