alika - 1:15 am on Jun 8, 2010 (gmt 0)
It really depends on your site.
Some forum sites, which attract repeat visitors who in turn develop rapid ad blindness, are better monetized by CPM ad networks. I know of some that makes only a few dollars a day with Adsense, but earned thousands with the like of Tribal Fusion or Burst Media.
My sites just don't work with CPM ad networks because they don't attract the millions of visitors that others get. However, my sites attract an audience that are responsive to ads. They also view the ads as an additional resource to the information my sites have. Hence, Adsense works essentially well for me.
However, there are sections where Adsense really does poorly, and I removed Adsense and replaced it with other ad networks. There are also ad formats/placements that I gave to other ad networks (e.g. bottom of the articles using Chitika's mega units) while giving above the fold prime real estate to Adsense.
Like everything about Adsense - test, test and test.