I have heard good stories about Redit

You can choose for yourself which platforms suits you best.
It's sensible to join a few, if you dislike one, you probably are not going to use it fully too, and then it's a waste of time.

https://en.wikipedia.org/wiki/List_of_social_networking_websites

Hi Chan.... here's the thing......

If like most of us, you are building your website with SEO (organic search traffic) in mind, yes.

With the latest Google Algorithm update, it has been proven that "social signals" are now part of the factors that determine where a web page will rank. The social signal portion of the Google search mechanism is currently small, but growing. And, as a frame of reference, i would say that it plays about a 20-25 % role when all other aspects are included.

Much of the new social signals role comes from Facebook, LinkedIn, Twitter and most importantly Google+.

I have seen a change of Google+ followers (increase of 200) create a 15% rise in rankings for a webpage.

Now, this percentage is NOT the same for Twitter. It's much smaller....but, most of us SEO experts agree that all the major search engines will be look at Twitter much more so in the very near future.

So, the bottom line is that it won't affect things very much now.... but, that is due to change soon.

I hope this helps.

Peej