Put all three into your arsenal to drive the highest levels of traffic to your site. Each is different and you may have to tailor your style depending on which one you are But, using all three will be the most effective tactic. Each one has its' own benefits and drawbacks but using as many social media sites as possible will improve your exposure at the very least.
According to my opinion, Facebook is best when compare to Google plus and Twitter. Because Facebook has more features and applications.
Facebook always stands at first place due to most of them use Facebook.now twitter stands at second place.
I think each one is better for different things - i prefer Facebook for personal use, however i use all 3 for business.
I think they all have different strengths. Facebook - just about everybody is on it (good for keeping in touch with your friends and family) Twitter - easy way to see what is hot Google+ - brilliant at sharing content, its a good way to follow alot of blogs
Facebook is best now a day ... but let me tell you that Google Plus is now preparing to beat Facebook soon ...