Hey Nicole!

The best platform is the one that tells your story the best.

For us, Facebook has been fairly successful. (We work primarily with video and media.)
Most of the photographers we work with however, rely heavily on Instagram.
B2B Sales and Recruiters? Usually LinkedIn.
Home Decorators? Pinterest.
Web Developers? Twitter.

My advice would be to follow a few of your competitors and see what platforms they are focused on. Learn where your demographic lives and what they engage with. Then test what sort of posts gain traction using a few analytical tools and see where things go from there.

Best of luck!