In my opinion Facebook is the best for personal use and LinkedIn for business. Both websites offer more features than other social media websites and get updated regularly to ensure they are user friendly and secure.
Social media is changing quite a lot. I vote for facebook as the best social media site for now, particularly for business pages, however, google is changing the way website content can be found and ranked, so I definitely think it is best to get onto Google+ ASAP. I'm quite a fan of Instagram, its a bit voyeuristic, but also great for escapism to see what the rest of the world is up to!