I have used chart.js in my projects several times but I have never used d3.js. A lot of people say that d3.js is the best javascript framework for charts but none of them is able to explain why, especially when I want a comparison to chart.js.
I have found this: http://www.fusioncharts.com/javascript-charting-comparison/
but it is not what I was looking for.
Does anyone know about a comparison of these frameworks in terms of usability and performance (only for charts)?