A lot of our library additions are from fulfilling customer requests and needs (see the change log from 1.4 to 1.5 to get an idea), so if anyone finds functionality particularly lacking in the diagramming libraries they use, I'd love to hear about it.
Output is also super simple with no frills - even though the website doesn't sell that very well.
(edit: a link to my own simple, albeit demo, page using the library: http://nlpviz.bpodgursky.com/home)
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!
Outside the network module, I have no feedback on visjs.
Code example goes like something this:
// var scene = (some babylon js stuff here, - sorry, messy)
var WE = new Worldedit(scene);
.select([-4, 0, -4])
.move([0, 2, 0])
.select([0, -5, 7], [-1, -1, 6])