Best course on Coursera is being repeated right now: A Brief History of Humankind. Mesmerizing professor; provocative topics; deep thinking! Dr. Harari is one of a kind.
Hopefully will be repeated again: Constitutional Struggles in the Muslimorld. Professor Afsah is one of the top two Coursera instructors in my book. Gives a deep historical background, and is open, unbiased, and provocative.
Emergence of the Modern Middle East: will be repeated I understand. Professor Susser is exceedingly unbiased and thoughtful, and the course itself, like Constitutional Struggles above, is truly enlightening in respect to today's situations.
Surveillance Law: going on right now. Hippie-looking instructor who is organized, original, interesting and absolutely clear on a rather confusing topic.
Hard to contain myself on this question, since I've completed (not for certification) 13 courses, and have begun and dropped only two: one due to my own inadequate biochemical background; the other because of sheer boredom with the two professors giving the course.