I don't know the answer to your question, but... Google AdSense probably dominates the publisher market at this point in terms of impressions and # of sites that it runs on. Reach- eh. But its a brand. Google, Yahoo, and Microsoft are the big 3 in advertising. They own parts of most of the other companies- or directly affect them. For example, CPX runs on Right Media, which is where it grew large. RM is owned by Yahoo. AdBrite is smaller than Google, obviously. Bidvertiser is extremely small, far smaller than AdBrite. The Bidvertiser brand is also less well known. It doesn't mean that these are worse networks, its just that they are smaller. In fact, they may be better than the big ones.