There are so many platform for social media network but for the business purpose, LinkedIn is the best option where numbers of people from highly organized company are visited for daily basis and built a strong business relations.
To start with all is well should be the perfect answer here, for you should use all of them effectively. Each social media network has it's own rules/benefits, and hence one cannot be better than other on general. So in the end it all depends on your domain (business), target audience and marketing strategies.
Facebook will be amazing if your target audience are mostly youngsters. Twitter has more to do with text engagement and it helps you target and interact with larger clients with ease. Linkedin is the best place for B2B business firms, recruitment business, and any other business that targets working professionals.
Note: There are more to the story of Social Media, Youtube, Pinterest, SlideShare and more sites are there to showcase your business and interact with your target audience..!
Facebook, google+, twitter these are very best for business. After that pinterest, linkedin, stumble upon, reddit etc are best social sites for business.