The adoption of commodity apps is now completely driven by fashion. There's no "best" photo sharing or video sharing App - what you use (snapchat vs. instagram vs. facebook vs. flicker vs. 500px...) is completely dependent on your sense of taste, and how the App is perceived by your peers and in the culture.
There is no "best" social network in the same sense that there's no "best" pair of jeans for everyone.