You can say PopAds and PopCash are excellent choices when it comes to Pop-under networks, based on their high CPM rates (due to advertisers volume), ad inventory for worldwide traffic, daily payments with a low minimum balance requirement, support for any niche (incl. adult).
Out of personal experience, both networks offer decent CPM rates but sometimes one network have the edge over the other depending on your website visitors demographics, that’s why my suggestion is to always test both on each website and even consider doing periodical tests (don’t forget that CPM rates change all the time), that way “you won’t leave any money on the table”.
|Minimum balance requirement||$5||$10|
|Payment methods||PayPal, Payza, Payoneer, Bank Transfer, Wire||PayPal, Payza, Paxum|
|Accepted website types||All types (incl. adult)||All types (incl. adult)|