Horde or Alliance? why?

yeah, in most cases alliance are better at raiding while hordes want to pvp. Blizzard wanted to balance things out, but it was never balance, they miscalculated many factors that came into play. If anyone knows the history of Wow, the alliance( that time only wif human, dwarf and gnome, nightelf was on their own) was the fraction that plays a major role in the story of Wow, they fought the burning legion, now they are fighting the scourage. The alliance has more role to play in the storyline. The nightelf defeated the first burning legion on their own, defeated the second with humans and orcs. If anyone plays Warcraft3: the frozen throne, you might know that the hordes don't even have a proper campaign on their own. But blizzard certainly wants to balance this out so their created a bonus campaign, if not the horde fans might not play it and blizzard will lose a lot of income. On the other hand, the hordes were toys of the burning legion, they were corrupted by demon lord Kil'jaedon and had been used as a tool for the invasion. The orcs turned their beloved outland into a wretched place. Throughout the invasion, they gain many victories but finally failed. Azeroth was safe and the order of the Silver hand ( lead by Uther the lightbringer ) drove them back. Sum up the betrayer of Ner'Zul, the hordes were greatly weaken and considered as a failure by Kil'jaedan. Not until Thrall freed his people from the curse, the orcs finally regain their belief in shamanism. However, outland is not suitable for them to build their capital. Therefore the hordes decided to settle down at Azeroth (often in conflict with the nightelves over lumbers). And see, the hordes basically had no enemy to fight, thats why they would point out the alliance as one of their enemies (PVP). And also, influenced the players decision in choosing their fraction. But the alliance is different, the alliance was in war with the scourage, (thats how warcraft 3: the frozen throne ended). And you had noticed, the scourage engaged more battles with the alliance than the hordes, that shows that the alliance is the scourage's priority. Basically Arthas doesnt even care about the hordes. And therefore, most PVE players will go after alliance, and choose to play with the story line.