Simple statistical answer would have to be Blue... the scales tipped by 2 player freestyle where the 2nd player (blue) goes 1st and has a distinct advantage... or so i have heard, I never played a 2 player game myself...
But as for a color advantage in actual gameplay, if you are playing strategically challenged opponents then sure... for example, being blue in europe would be a big plus... I have also found that
certain troop counts on
certain countries in
certain colors can be easily overlooked... but seriously, how many players even think of such stealth tactics... I would love to see the statistical results from 6 player games to see if any specific color really does bear out an advantage.
and black jesus... i must point out that since you would not meet me on my terms (6p classic, esc) we engaged on turf unfamiliar to me (6p world, flat, fog
Game 2907461 )... and in our only engagement, your black blood was splattered all over your pink uniform, your rotting corpse laid beside my other enemies until, in the end, there was only myself and my strategic superiority.

hehehe