US teens have rated Snapchat, Instagram and TikTok as their favorites apps in general along with giving them the highest marks for engagement, according to a survey of 5,200 individuals in 41 states conducted by Piper Sandler. The firm's Taking Stock With Teens survey also reports that teens spent an average of 12 hours per week on social media and, while Facebook had been declining somewhat the past couple of years, it's witnessing slight rebound.