For quite some time I'd been using cpmStar for advertising, recently after some recommendations I switched to EpicGameAds.

So far the results have been slightly improved eCpm on one or two different advert sizes but on the other it's actually gone done. At the moment I'm testing so I'll leave it going but it's well worth a try to see how conversion rates are effected on your sites.

The only down side for high income earners is that they don't currently support bank transfers/wires but are happy to pay via check if you reach the $1000 a month mark which is reasonable.