Clicksor ads contain malware/virus/redirects. Moreover they report far lesser impressions compared to actual and their rates are pathetic to say the least. It should better be avoided. Fidelity is pretty decent. Good fill rate (around 80-95%), average eCPM rate (around $0.15) and excellent publisher support. They also offer option for passback tags to monetize your unsold inventory. You may refer to this article for a detailed review - http://adsreview.in/fidelity-media-publisher-network-review/ Regards, Deb