Have used Highcharts, MxGraph and Dagre-d3 in work projects and I should say with more support (active development) to Dagre-d3 it would be way too good. While considering for one of our projects (https://github.com/caskdata/cdap/tree/develop/cdap-ui) our first choice was dagre-d3 but since the github page for it clearly says No Active Development going on, there was a bit of hesitation. Turned out to be pretty good! :)
OP can definitely consider taking adding Dagre-d3 to that list, its free and it figures out the space problem (how to space out your DAG) based on the input. We don't have to figure out where to draw which node and how to draw the edges!
If active development is a concern, you may want to consider ZingChart (http://www.zingchart.com )
They release new builds on a quarterly basis. The support is pretty responsive, too.
OP can definitely consider taking adding Dagre-d3 to that list, its free and it figures out the space problem (how to space out your DAG) based on the input. We don't have to figure out where to draw which node and how to draw the edges!