AppWall - Chartboost vs AppBrain

Hi all,

I am considering implementing a More Games button that will open an AppWall ad. Which of the 2 options would be better - Chartboost or AppBrain? I know I can mix & match, but I am trying to play with only a few ad networks now, in order to get the money rather than splitting it.

The app is a game that targets users between the age group of 15-35.