Media.Net is often interpreted as the best Adsense alternative. They recommend you use media.net in case you are rejected by Adsense. Some even say you should use Adsense and Media.net at the same time. Adsense is PPC program, which means you earn for every legitimate clicks. I don't know what is the earning modality for Media.net, perhaps it is between CPM and PPC.
Have you used Media.Net?