I use a few different ad networks. I have tried others also. The trouble I have had with some in the past are, they would redirect my readers to a spammy page, or they would do one of those full page things that you had to click on skip ad for. Anyway I have found a few that work for me. Ad networks are based on either ad clicks, impressions or both.
So here are my choices for the best ad networks.
Google AdSense is by far the best, this one pays out at $100, and you get paid for clicks and impressions.
Then there is Sovrn this one is per impression, the payout is $50.
And last but not least is MediaNet, they are powered by Yahoo payout for this one is $50.
Google is my favorite to say the least, they have the best payout and most relevant ads.