Analysis by AudienceProject has revealed the social media apps which are used most often. Top of the list is Facebook, with 53 percent of the 1,757 U.S. respondents saying that they access the mobile app several times a day – pretty far ahead of its competitors. In second place is Facebook-owned messaging service WhatsApp with 44 percent. The rivalry between Snapchat and Instagram is too close to call in this regard, with Snap’s app claiming a slight edge.