Hi.
I have my first app on Android, and release it 3 weeks ago. And for now, I'm using AdMob... But users are really low (about 20 active per day). I was just wonder, of other developer experience. Because I have some WP apps, and my experince is, that Microsoft have biggest cpm (but have lower fill rate), Google have quite low cpm. But for a while I try smaato and it have even lower cpm than Google. But for now, it seems, that on Android there are bigger cpm than on WP (for same app, but can't be sure for that low count of impressions)