I really like dform's flexibility. I have been able to add every HTML elements that I've needed with the same syntax for every one, making it very simple to stick them into PHP loops to generate the elements based on the query results. I've learned a lot about writing jQuery functions while using it.
FusionCharts is very specific in what it does, and is compatible with many languages. I have actually learned to use it's classes in both PHP and JavaScript so that I can create any part of the chart I please in either language, and it is capable of transmitting data in both JSON and XML even though it uses XML internally. I've briefly taught myself the differences between the formats and have gone from manually creating XML, to learning that JSON is way better, to automatically converting my arrays into JSON data.
I feel that I've kept my project quite lean indeed, and was actually worried about not accomplishing a lot, not being complex enough. But I have intentionally been trying to avoid complexities so that I can make it easy to pick up and use, just include jquery, dform, and the FusionCharts.js/.php (and source code).