It's always interesting and valuable to explore Apple's Best of 2014: Top Lists. Below are screenshots of the Top Free, Top Grossing and Top Paid iOS Apps. You'll notice a few things:
Top Free: it's a list dominated by big brands. - Facebook has #1, #4, #5 and #11 with Messenger, Facebook, Instagram and WhatsApp respective. - Snapchat is #2. - Google has #3, #7, #12 with YouTube, Google Maps and Google. - Pandora is #6. Spotify is #9.
Top Paid: There is some variety here, Of the top 20 - 14 are games - 4 are Photo and Video - 2 Health and Fitness
Top Grossing: This gets slightly more interesting. - All of the top grossing applications feature in-app purchases. - Games still dominate: 18 of the top 20 are games. - Pandora is #3 overall and the only of the Top Grossing to also be a Top Free app. - Zoosk is the lone other top 20 app that is not a game. - Of the games, big names matter: King owns 3 of hte top 8 apps and SuperCell has 3 of the top 11