Since this thread seems to have arrisen from the dead; I'd like to put in my two cents. The answer is dependent on what your website is about. Google+ is a great start because of how it ties in with the rest of Googles products and services which will help your website be "Google official" - thus minorly effecting SEO but the rest will all depend on the audience you are trying to get. You…
Not so long ago, "the older SEO" decided the website advertising globe. This was during the earlier, revolutionary times connected with website marketing -- before it absolutely was normal intended for a small business to get a website as well as some time before the granny got an online presence which could competitor a youngster. The particular aged SEO approach centered all around one particular major factor: link building. Nevertheless currently, link building as a direct SEO method is totally useless. The fact is, Google provides identified smart ways to measure the particular reputation of your respective website: it truly is referred to as SMO. And the best social media sites are Facebook, twitter, linked in, google plus. And recently came across a matt cuts you tube video on SMO in that i explain google plus is most effective site for SMO.
Since this thread seems to have arrisen from the dead; I'd like to put in my two cents. The answer is dependent on what your website is about. Google+ is a great start because of how it ties in with the rest of Googles products and services which will help your website be "Google official" - thus minorly effecting SEO but the rest will all depend on the audience you are trying to get. You need to remember that the reason SEO exists is to get good rankings in search engines; we want to get good ranks in SE to drive traffic; the reason we drive traffic is to be found; the reason we want to be found is to convert visitors into paying customers (whether through direct lead conversion, using our services offline, or by making money through ad revenue).
For example; Instagram can be extremely effective - but only 17% of users in the last half of 2013 were reported as being adults with 37% of those users being in the age group of 18-29. The majority income bracket in the group of adults was $30,000-$50,000.
If your website is aimed at selling retirement properties; Instagram will not be your most effective social media platform. However if you are selling alcohol then you are definitely on the right path (statistically speaking when you combine those stats with the stats of consumer consumption of alcohol).
That being said as a part of your social media strategy you shouldn't just ask the question, which social media platforms are the best? You should go the step further and research who your users are and what social media platforms are going to be the largest impact in getting those users to increase your bottom line (ie. revenues - regardless of the source of your revenue).
Lastly, prior to finalizing your social media marketing plan you should also research and begin estimating your ROI (Return on Investment). If you staple yourself to facebook, you will come to realize that organic growth of your facebook page is going to be next to nil with the changes to facebook in the last 12 months. They have changed it to force Companies to invest in FB advertising to see the type of results that we all want. This means that although Facebook might be the biggest and most popular social media platform, you better be willing to pay to get the leads you want to your website (and believe me, it does add up pretty quickly if you dont have a solid marketing plan). If you are looking for viral, you may find that investing your time and efforts in Linkedin, Twitter, Pinterest, or Youtube might be far better when you begin adding up what its going to cost to get every user and get the exposure you want.
From SEO persepective, Google+ will be very useful. If your targeted audiences are limited to some particular city, you can do exceedingly good if you optimize the page with the relevant business keywords.
Also any Link you shared on Google Plus, get indexed in less time.
There are other social media sites that still work well, depending on your niche, like StumbleUpon, Digg, Reddit, Indulgy, Polyvor, Instagram. It all depends on what you're into! I am in a visual-rich niche, so any of these sites welcomes me with open arms.