What is your favourite 3rd party WinForms.Net graphing tool, and why?

Question

By graphing I mean bar charts, pie charts, line graphs, that sort of thing. I've used a couple over the years, but what is your favourite and why?

One tool per answer please (to make the voting easier :o)

Answer 1

If your goal is a simple graph and you need little control over how it is rendered you can easily get started with google chart api. You just putting an img tag on your site passing parameters in the querystring on the end of the url. You can even customize the output colors etc.