Highcharts provides 20 different types of [charts](http://www.highcharts.com/docs/chart-and-series-types/chart-types) to choose from, and they make it simple to [combine](http://www.highcharts.com/docs/chart-and-series-types/combining-chart-types) chart types.
Ranked in these QuestionsQuestion Ranking
Pro Robust API
Pro Tons of styling options
You can get extremely granular with the styling (which is very CSS-like). You can customize pretty much any aspect of a chart, so they can match your application or website perfectly.
Pro Easy to try
ZingChart hosts the full version of the library for evaluation on their CDN for you to try in just a matter of minutes.
Pro Angular wrapper
Pro Free branded version
There is a free version available, however it's branded. Licenses start at $249.
Pro jQuery wrapper
ZingChart has a well-built and excellently documented jQuery wrapper, making it easier to integrate ZingChart into your jQuery code.
Pro Handles large data sets without bogging down
Pro Excellent browser support
Highcharts supports all modern browsers (including IE6 and up), iOS and Android.
Pro Lots of good examples
The site has a selection of good examples that will help you get started quickly.
Pro Library to support Microsoft .NET
Compatable with .NET framework 4+, can develop graphs from server side for ASP .NETand ASP .NET MVC applications.
Pro Good documentation
Very handy with examples and explanations.
Pro Supports multiple Y axes
Important for trend correlation, eg. comparing number of clicks to sale amounts. Not same scales / units.
Con Not open source
Con The free version inserts a watermark on all charts
Either their watermark is on all the charts or you have to pay expensive license fees.
Con The examples are not that great
For instance, example's JsFiddle may get stalled when loading.
Highcharts is not free for commercial projects, with a starting price of US$590 for Single Developer + Maintenance & Support