The hot new thing in my office today is Vega, a library and “visualization grammar” for making D3 more declarative and potentially easier to use. What rocks my world about it is the ability to render to either SVG or Canvas. You can see that in action on the Vega Live Editor. Canvas is going to be much more efficient for complex visualizations, provided you don’t mind that browser-zoom won’t be all vector-iffic.
I had largely been sticking with HighCharts for standard visualization types that don’t require fancy time-series animation or major style hacking. This may finally move me to D3 full-time, at least once we have a richer library of default configuration objects for those kinds of charts.