I started out as alliance, rerolled horde after faction change was available and honestly.. best thing i did since i started playing
My impression of alliance characters is pretty much what is being shown in this thread, they dont like horde because they dont like the looks... just lol. The other one i hear is people playing alliance because they want to be the 'good guys'
Cities? Yeah alliance like IF/SW because they like to have houses and buildings that look like houses and buildings and really might be better suited to a Barbie online MMO, Orgrimmar beats the crap out of both IF and SW hands down since the expansion, It looks like the designers spent most of their time on Org and then suddenly remembered in the last few weeks they also needed to do something to SW
Yet if you actually play horde you realise from the lore and storylines that go with them that actually the alliance are more like how most of the world sees america today, they think they are the good guys but in a lot of situations they are actually douches. Take the wrathgate, I played through that questline first as alliance and again as horde and it basically shows the alliance to be jumping to conclusions, angry, emo etc etc. You also get a sense of this if you read the books
So yeah for me its horde because there is more maturity and less vanity. And besides you cant beat a warcry like FOR THE HORDE!
I will say there are two things and only two things i miss about being alliance
1) Nelf flight form, altho all other troll forms are cooler
2) Having more people to gank (because there are not many alliance left on my server)