Outbrain has amazing high quality publishers and I have always liked their platform.

Zemanta provides an easy way to access virtually all sources of content ads via one platform. Zemanta has access to most sources of native inventory including Yahoo! Gemini and Outbrain making it an easy way to manage and achieve maximum scale with native advertising. It also integrates with Google Analytics to help optimize for post-click metrics such as time-on-site and bounce rate to help optimize for the best quality clicks possible.

Great service from reps. Everyone I’ve worked with has been very helpful.