You're right, it's just a feeling I have from how present Horde fans are especially at Blizzcon and from polls like that http://www.mmo-champion.com/poll.php...do=showresults. My feeling is 66% Horde 34% Alliance.
Also the data doesn't take into account how many people exclusively play Alliance or Horde or play both.
edit: most poll results seem to be at Alliance 45% Horde 55%
http://www.mmo-champion.com/poll.php...do=showresults
http://www.mmo-champion.com/poll.php...do=showresults
And this one 60% Horde 40% Alliance
http://www.mmo-champion.com/threads/...iance-VS-Horde
but there is one poll that takes into account that some players play both factions, there it's 45% exclusively Horde, 32% exclusively Alliance
http://www.mmo-champion.com/poll.php...do=showresults
and this one has 50% Horde 30% Alliance with 20% playing both
http://www.mmo-champion.com/poll.php...do=showresults