On the custom side, d3.js has more chart types currently supported, but we've added more with this release and made extending / creating new chart types 100x easier. Previously custom work was much easier with d3, but the gap is now significantly reduced.
Can you expand on this a bit? From skimming the documentation this still seems firmly in the camp of a few charts with a lot of options, as opposed to d3's do what you wish model.
It certainly isn't to the d3 level yet, but almost everything is exposed and extensible with the new API so you can create most any chart you can think of.
For custom stuff I use D3, but for the "standard"-charts I use Highcharts.
Edit: Seems like Chartjs is MIT, Highcharts is only free for non-commercial.