Comparison between svg and vml based on user comments from StackOverflow. You can specify the renderer parameter as canvas or svg while initializing a chart. Raphael is ranked 3rd while Snapsvg is ranked 6th.
In the DOCX file it has Shapes SmartArt which we can render as SVG or VML.
The most important reason people chose Raphael is. 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. HTML5 canvas VML vs. I dont need the VMLIE support in Raphael or the plotting abilities of jQuery SVG.