According to me Facebook is my favorite social network because here we can share images, photoes, videos, contents and also give Facebook ads which is very interesting and attract the viewers towards them. Twitter is one social network which I like the most, here we can tweet.
I am acting on four social networking like as Twitter, Facebook, Linkedin, G +. I like sharing my status and make friends on Facebook. I don't like G+. For my job, I prefer Linkedin. In here, I can change all thing of business to everyone.
I can say that Facebook is number one for many of us, lots of people used it, you can join groups and like pages according to you niche, you'll have more traffic and visits thanks to it ( I did ), after that come twitter and G+.
if you have a gallery instagram and pintrest are good
1) facebook - for personal communication
2) Vkontakte (russian speaking) for personal communication.
3) LInked in - ideal for commercial communications
4) Xing - Good but not ideal for commercial communication.