Hi. A few months ago, I explained my experience. I am going to copy this text and modify a bit because some has changed since this. I have referrall links but I have written about some others ad networks with out referral links:
Ok. The links belows has a code. The code is for both receive a bonus and I’d appreciate it if you register you do with these links. I tested airpush, the eCPM was good but fillrate was very bad and the listeners for use an other adnetwork when they have not an ad for you working very bad. So we don’t use airpush.
My apps are most from LATAM so my eCPM is not the highest.
AppNext. There is not referrall links. It is great for the app entry (eCPM 1.5-2$) but only in this way. Has listeners. For some countries of Latam the fillrate is 100% (Usa and europe ofcourse) but for others, like Colombia, fillrate is bad buet it is solved by the listener and redirecting to an other ad network.
StartApp For banners was not very well but is getting better and for fullpage works very good and ads are very nice. I have 1,5 - 2 eCPM. The fill rate is near 100% and you have a listener to use an other ad network if it fails. You could use search box which they pay for each one that install it (accept an eula). If you use this you will receive a bonus in your fullpage revenue (25% I think, but not remenber exactly).
MobileCore. Could be the best ad network that we have tested. They has fullPage but not traditional banners. For USA my eCPM is 6$. For all my apps is 1,5$ but most are from LATAM. Is very new. They reply all your mails even saturday or sunday. The CTR is very high. They have an slider (with brench as share or rate us) and other kind of ad (Sticker). Offerwall works well as exit too. Fillrate is 100%.
Admob. Is great eCPM, similar than StartApp and MobileCore but they comunication with them is impossible and one problem with them is very hard to fix it. We don`t use admob now, but we have used. I think is better for banners which are the best eCPM I have seen.
LeadBolt For full pages works well for some countries (USA, Europe, Australia…) but when it works very well (at least for us) is in exit and exit ads. Is a dialog yes/no as the revmob pop up.
RevMob. It was very bad in January but now has returned to their great eCPM. Banners works a bit bad. It is better for interstitials and the link.
We use 1/2 MobileCore and StartApp and LeadBolt for some entries an exits. As the ads are different that makes that users cliks more that means great CTR and better eCPM because the user does not whatch allways the same apps. Wehave tested a lot of adnetworks and the problem is that most of them gives good ecpm only for USA and Europe. Having 2$ eCPM for USA is very easy, but having 1$ eCPM for Brazil or 0,8 for Colombia (as MobileCore does) is very difficult.
I hope you find this information interesting and sorry for my english.