"best" = had a tangible post-effect on my life choices & thinking processes, and the content was highly educational

(sorted by when I watched them)

2014:

none taken, and as of April 2015 I see it as a mistake. I still consider it an inefficient form of learning for me, but within the context of my life it's a necessary measure.

2013:

• The Language of Hollywood: Storytelling, Sound, and Color (Coursera, Wesleyan University), completed fully
• A Beginner's Guide to Irrational Behavior (Coursera, Duke University), even though I didn't watch everything (only 90%?) and didn't read everything (only 5%?)
• Nutrition for Health Promotion and Disease Prevention (Coursera, University of California), watched fully, did only that one important exercise about tracking nutritional content of your food intake for 24h (was eye-opening)
• Social Psychology (Coursera, Wesleyan University), even though I didn't read everything (only 60%?)