Most of the [examples](https://github.com/mbostock/d3/wiki/Gallery) provided are by the author, but there's also a great community writing plugins and more examples.
Ranked in these QuestionsQuestion Ranking
Pro Works with older browsers
Because Raphael supports rendering VML + SVG, it is one of the few drawing libraries that is backwards compatible with older browsers that do not support canvas.
Pro Built in animations
Several built-in animations (such as ways of easing) are provided for you out of the box, but Raphael also allows cubic beziers for more complicated easing functions. Any drawing object property can be modified making it similar to css animations in jQuery.
Pro Every object is interactive with events
This style of handling objects makes Raphael a good fit for rendering interactive diagrams and charts that can also interact with other parts of the page.
Pro Easy creation of charts with extension
gRaphael is a Raphael extension to help you easily create graphs and charts.
Pro Huge number of examples online
Most of the examples provided are by the author, but there's also a great community writing plugins and more examples.
Pro Large community
D3.js is a very popular tool with an active community, resulting in plenty of learning resources and fast responses to questions.
Pro Doesn't require a proprietary framework
D3's emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework.
Pro Versatile library for manipulating data on the DOM
Pro Very flexible join paradigm
Can be tricky at first, but once learned, data manipulation and binding can easily generate complex visualizations for massive amounts of data.
Pro Great for highly interactive scenes
D3.js offers incredible levels of interactivity.
Pro Backwards compatible
D3.js is intended for modern browsers, so supports IE9 and above (IE8 with an additional library) as well as all the other modern browsers.
Con Complicated, confusing documentation
The documentation is often not clear and lacks practical examples.
Con Can be difficult to get support
Online communities for Raphael are small and inactive compared to other drawing libraries, and many issues opened on github are never addressed.
Con Steep learning curve
The complexity and flexibility of D3.js results in it being a time-consuming tool to learn for many users.
Con "Selections" are elegant, but somewhat hard to grok
Selections are core to working with D3 beyond the basics. They're powerful and useful, but require new developers to get up to speed (e.g. set aside 30m to read and digest: https://github.com/mbostock/d3/wiki/Selections) and if used in the context of a larger application will result in a portion of the code using different patterns than the rest, requiring a translation layer in between.