Ask HN: Which site is your favorite social network and why?

Never mind the site that most of your friends use... Is Facebook, Myspace, Orkut, Google+, Hi5, Twitter or LinkedIn your favorite social network?

And, Why? Do you like your favorite social network for its features, security, simplicity or another reason?

I'll use your feedback to build a better general social network. One that will allow people to communicate more naturally online with ease.