adarnk hit most of my points.

1 ->> Anti-aliased lines and labels.
1994 called - it wants its fonts back.

2 ->> Better-looking charts
Given the choice between displaying a composite line chart using DBD::Chart or Dundas I can see how it really would just depend on what you are trying to do.

3 ->> Object-oriented API/DOM
I think a DOM-style API to the chart would be great.

4 ->> Smooth vector-style colors, gradients, alpha and shading
This is pretty standard across even low-end commercial packages. There's got to be some way to generate smooth graphics.

5 ->> Professional Appearance
When I am making a chart for myself to see how many emails a server is bouncing, I'll use whatever tool will get the job done. This might just be HTML.
However, when I am putting together some charts for a commercial tool (i.e. - CRM suite), I would like to have something that looks as good as the rest of the design (and still presents the information in a concise way).