First of all horde racial abilities COMPLETELY own alliance ones, you cant compare undead priests Will of the Damned racial (which will break any kind of stun/charm/fear) and Devouring Plague racial (another powerful damage over time spell) while at the same time alliance night elven priests get a most magnificent +1% dodge AND starshards which are simply UTTERLY useless. Orcs are semi-resistant to fear, humans have increased stealth perception. Tauren have warstomp (5s area of effect stun) dwarves have useless stone form. Anyhow, it all boils down to 'fear whoring', horde will always use several warlocks to area of effect fear alliance team, and while the entire alliance team have no control over their characters (which is game breaking in itself) they kill one by one by concentrating fire. Alliance has no means to counter this (you can use anti fear trinket only once in 5 min) and can't do the same on the horde (horde have been made as fear resistant as possible). [WoW, M, 27]

Horde tend to get better PvP racials and Alliance tend to get better PvE racials. Fear Ward, for example, is a huge bonus to Alliance guilds attempting Onyxia, Nefarian, or Magmadar (raid bosses), while War Stomp is a very good PvP skill. [M, 17]

PvP rewards are harder to attain and take longer to get than PvE rewards from raiding instances, making it so that, generally, Alliance is better geared than Horde, since Alliance seems to be better for PvE content. [WoW, M, 20]

On my server it's pretty even, but only because the alliance is miles ahead of the horde in terms of PvE progress and gear. If 2 evenly geared and skilled teams faced each other I'd say horde would win as we have better PvP racials. [WoW, M, 18]