In the time, I saw that for my contents ( we have to choose our "channels" on how they work for different contents that we want to share and to catch the right target) facebook and twitter are working better than others. The first because it help me to connect with my local community using my profile, the second because the users are in the right age and interest to share my "products" ^_^ Instagram is good for me because when I use it I  can share the same content also on twitter and on my page on facebook ;)