These Are Not Social-Lites
According to HubSpot's "Social Media Tips from Around World" Ebook, the top 3 social networks are: 1. Facebook 2. Twitter 3.LinkedIn
Which social media you use depends on who you are talking to. Facebook and Twitter are best for B2C, LinkedIn for B2B.
YouTube is second most used search engine and is owned by Google, so content on YouTube will also be indexed in organic search. Although Google + is not widely used but +1's will help your content rank well in SERP.*
Tumblr's massive growth continues at 35 billion posts predicted by the end of 2012. Tumblr's demographic skews young and female. 54% of the users are female, 26% are 25 to 34 and only 14% are 45 to 54 according to Ad Age Insights.
Pinterest skews female and young also with 68.2% of the users female and 27.4% aged 25 to 34.** Of all the social medias, though, it also captures the highest percentage of the 45-54 group at 25% compared to Facebook at 12%. It also keeps users interested – matching Facebook as the most time spent per month at 405 minutes, according to blogherald.com.
*HubSpot "Social Media Tips from Around the World" www.hubspot.com
**Ad Age Insights April 2012