http://coh2chart.com/
Go ahead and check out the win-rates for 2v2's
All these charts show which faction people prefer to play...
If you look at an MMO lets say... Starwars the old republic, 90% of the players play Sith, the classes are an exact copy on each side, but everyone likes the bad guys. Cool looking gear and ships, In this case, cool looking tanks and uniforms.
+ this argument is totally defeated by the overwhelming fact that...
Allies win most tourney games by a large margin.