I strongly suggest testing the same in a month long process and finding out which Ad network gave you the best CPC in the same ad positions.
Later on, you can change the ad positions and run the top 3 networks which gave you the best CPC. You will have to experiment but it has its benefits.
All of the above are more US focused. Chitika for example has majorly US CPC. So if i were to pick, i will pick media.net, clicksor and chitika to compete first. But then again, i have only heard about these and have not moved away from adsense since the last 5 years.