C3 is also a D3 based reusable chart library. With C3 it is easy to combine different chart types and the charts are very good customizable. Sadly the API is not fully documented but there are several code examples.
DC uses crossfilter for filtering and grouping heavy amounts of data. The library is also a good choice if you want to use charts in order to control other visualizaions. As you can see in the example the charts are for displaying data but also for controlling the state of the current view.
Taucharts has "a focus on design and flexibility" as they say. A nice feature, I often missed in other libraries, is the possibilty to add trendlines to a certain chart as you can see on the screenshot above.