You could try
plugrush for start.
To answer your question,while plugrush is close to have a title of "best broker program",there are some things which are still missing there,so in the end best is combination of traffic brokers,because they dont have matching prices,so what you could do to maximize your earnings,to send traffic based on various criteria like country,isp,type,etc...So for example you could send usa traffic to broker A and german traffic to broker B.