Best World of Warcraft Realm for city raids?

Well, I really like to go to other fractions cities, and I was wondering what realm is the most active/fun doing this. Don't just say your realm.... say one that answers my question. I am planning to be a night elf druid, and you can help me out with that if you want, like explaining what is the best for druids. Thanks sooo much! If you need anymore information just post.