Facebook,Twitter,Linkdin,My Space ,likes is my Favorite social network sites.

Best Social Network is Google + , But There are lots of Social networking sites which are like,
google + , Facebook, Youtube, Twitter, Reddit, Delicious, LinkedIn, Stumbleupon, Etc.

i like facebook.it is the best social networking site.

Twitter
Linkedin
Gppgle+
Likes
Tumbler Is The Best Social Networking Sites.

Twitter and Google +

Facebook And Google + Is Best Social Networking Sites.

Twitter and google+

Social sites are the only hope for me these days as i am getting tough competition for keyword boosting. It is one of the best ways to get good traffic instead of wasting more efforts on keyword boosting.

Google+, Facebook, Linkdin,Yahoo,Twitter and etc...

Facebook and twitter is the best.

There are so many Social Networking Sites. For me the best: Facebook, Google+ and LinkedIn.

Facebook
Flockstation
twitter
linkedin
tumblr
google plus
instagram
pinterest

I think, my preference would highly depend on the type of communication I want.

To make professional connections, I would for sure go with LinkedIn and Google+.
For the informal communication I choose Facebook.