Anyone who played wow since the original will like horde more.
Back then, horde was mostly chosen by players who know the lore, and not by "zombiez R bad, ima be paladin" kind of players. Horde used to win all the battlegrounds simply because most of the players were much more mature and allways fighted in teams. I remember taking all of the flags in warsong guilch without any deaths simply because we allways worked as a team.
Most of the newbies have spoted that the horde is much more powerful, and switched. Or maybe it was the introduction of blood elves? i dont know.
But shortlly affter the release of TBC horde lost its charm. instead of getting free buffs or water from priests and mages, you are more likelly to be ninja'd in an instance. Instead of working as a team in battlegrounds, everyone just goes around killing random players for honor points.
I dont know, maybe some veteran alliance players will dissagree, but thats what I remember.