I feel like if you're trying to market a niche related to fashion I feel like Instagram is better than Facebook. Instagram has a lot of youth and teens who are impulse buyers compare to that of Facebook. Also you can pay big Instagram platforms to do shout outs about your product.
Where on Facebook you are just trying to get it out there with the HUGE audience they provide. Facebook is great with the opportunities they provide us, but I believe marketing on Facebook can be harder for newcomers. Facebook is a big place and will need expertise in marketing to achieve success.
I'm testing my campaigns on Instagram and they are working better for my fashion niche. One shout out usually gets me a good sum followers and sales (Depending on the person you paid for the shout out not all shout outs are successful).
Have you tried any of these, If so what do you prefer better?