According to recent study, snapchat is the most popular app among teenagers in US. A survey on 6500 teens in US to see what their opinion about the most important social network, 

# 28% voted for Snapchat 

# 27 % voted for Instagram which is a very close call

Leaving the rest for twitter and facebook. The study shows that teens tend to be more interested in viewing pictures and videos rather than text-focused media seen on Twitter and Facebook . Snapchat introducing things like Snapchat Discover and debuting live coverage at the Oscars,  as well as the popular face swapping feature and constantly adding new filters for images makes it interesting while other apps failed to do that. 

To know more, please read the article by written by Kelen Beck (Tech news reporter intern at Mashable)  -: http://mashable.com/2016/04/14/snapchat-teens-winner/#nxajcWykJSqm