I like Google + for posting about my forum/blogs as there is a more involved community of readers. Facebook is alright for backlinking. And, though I get some people reading my posts, there is more interactivity on Go...
My favorite site to use for SEO/blog promotion is Google +, but I also use Twitter and Facebook. Just recently, I learned about Pinterest, where you can pin photos from a blog post and would like to use that site more ...
