Have been using highcharts now for a few years. It's easy too start with, with preset examples (but who wants default colors anyway haha). I had to write an extra layer though to render charts more easily, directly from the dom.

Took quite some work but I don't want anything else now. Just set some data attributes and I can create pie's, line charts, and bars all on the fly!

It almost never failed me to customize it, editability is good and API doc extensive.