It depends on different factors. Generally, Facebook, Twitter, Google+, Pinterest, Linkedin, Reddit, Stumbleupon Generate huge traffic if you utilize these sites properly.
facebook , linkedin and twitter are the most popular site and most of the people use them but depends on you that hows you engaged audience on your status or post.
I think our posting should be interesting and effective.
It is true social media site helpuful in increase the traffic of website.There are lot of You can use social media site like:
Pinterest
Stumbleupon
Myspace
Facebook
Flickr
Twitter
Friendfeed
Vimeo
Houzz
Tumblr
Tagged
Delicious
Hi5
Folkd
Plurk
Mylife
Youmob
plus.google
Kippt
At present facebook is more popular social media site rather than the other sites. Twitter , facebook , linkedIn , Tumblr and Google+ are generate more traffic.