Ask HN: Best Ad Netowrks?

Hi HN,<p>I'm currently in the process of evaluating Ad Networks to provide revenue for my site. There are so many out there some free, some pay, some new, some old. I'm not even sure where to start!<p>Any fellow HN readers have any suggestions?<p>My Ideal network would have:<p>1. Base level of add track / performance metrics.<p>2. Geo Specific Ad targeting abilities.<p>3. Ability to sign up my own Advertisers.<p>4. Sales Force help. (Sales people to help sell space)<p>5. Flex banner size (Ability to post different sizes of ads)<p>Is there a service out there like this?<p>Thanks