Most powerful nation

[Baalz]

Well, I think the thing to realize is that the outcome of this game is determined by a lot of things outside of nation selection and the sample set is not near large enough to draw conclusions.

Some players were ganged up on and killed before they ever had a chance
Some players started in poor positions
Some players had abysmal luck rolls regardless of their scales
Some good nations were played by novice players

And of course the converse of all that is true to

Some players started out with relatively little competition whether it was from the extra water provinces or non-agressive neighbors.
Some players found easy allies early
Some players saw good opportunities as one of their neighbors was easy pickings due to an unrelated war front.

The huge amount of noise (from the perspective of determining relative nation power) makes a sample size like this meaningless.