When i started to play i chose a female Night Elf, i took the Alliance cause it was on the left, and i made a night elf because i don't wanted something common like humans, gnomes and dwarves were in my opinion too ridiculous, but it was my old brother's account, i finally took one and i just wanted to change, (and i also wanted to change my serv for a PvP serv) so i chose the horde.
And finally i prefer horde, i don't like Garrosh's horde and i hope that we'll kick him for a more level-headed and less warlike warchief, i really like the chamanic, tribal aspect of the horde, i also really like thoses little guys called gobelins, they're funky, i'm so glad that they entered the horde, how sad for Alliance, their counterpart for goblins are ... dogs.