When it comes to promote your business, I will always recommend Facebook and Twitter, because these the most popular social media sites, where you can reach numerous people and promote your business. Apart from that both the sites have different paid and free tools through which you can make your business visible to the target audience. So, in my view Facebook and Twitter are the best options to select, when it comes to promoting your business.
first check the most popular social platforms in your country. For example i am from India in India the popular social networkings are Facebook
pinterest - little bit users
snapchat will never popular in India and he doesn't want to give access to Indians.
like this in Your country filter out the social networks and manage the complete options. @LearnTheNew
I think you should use Facebook platform to promote your business. Because Facebook has largest audience than other social media platform. It is cost effective and result oriented platform. Facebook also provide analyzing tool by which you can monitor your business.
There are different social media channels are there for your business like Facebook,Twitter,Linkedin Pinterest & etc and facebook,twitter and linkedin are best for promoting and building brand to a business