IMO nvd3 is one of the better high-level charting libraries in terms of number of charts, out-of-the box styles and interactivity.

Honestly? Just write your own SVG code. If you inspect the elements the output data is super simple and easy to understand. NVD3 just wraps D3.js which just wraps utilities that output relatively basic data. Well, d3js is a data-binding system that's way too god damned complicated if all you want to do is make some simple charts which is how it's used 99% of the time.

I've spent more time trying to manipulate chart libraries into doing almost the same thing but just different enough to cause pain and suffering. Output your own path data and it's a million times easier.

For reference here's what I made: http://forrestthewoods.com/unbalanced-design-of-super-smash-...

It isn't d3 based (uses canvas instead of svg), but flot is fantastic as well:

http://flotcharts.org