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I was wondering what is the best Ad Agency that pays for every 1000 impressions. I have recently released my new app (Tic Tac Toe Go) and have been using AdMob, however I recently found out that they do not pay for impressions and clicks only. I would like to change this and was wondering what is the best ad agency to go for, ideally one which has a good fill rate and pays out on impressions. Thanks in advance, Raj