When comparing Snap.svg vs Highcharts, the Slant community recommends Snap.svg for most people. In the question“What are the best JavaScript drawing libraries?” Snap.svg is ranked 7th while Highcharts is ranked 18th.
Ranked in these QuestionsQuestion Ranking
Pros

Pro Pure SVG library
Pro Written by a SVG Guru and pioneer
Dmitry Baranovskiy also wrote Raphael (project now owned by Sencha), this is the updated modern version of that library. Dmitry also is a champion directly affecting the future of SVG standards with W3C

Pro Backed by Adobe
Adobe is backing the development of snap.svg
Pro Features
Supports the newest SVG features like masking, clipping, patterns, full gradients, groups, and more
Pro Good documentation
Very handy with examples and explanations.
Pro Excellent browser support
Highcharts supports all modern browsers (including IE6 and up), iOS and Android.
Pro Large and active community
Highcharts has a large and supportive community, resulting in a fast response from both stack overflow and the Highcharts forum.
Pro Lots of good examples
The site has a selection of good examples that will help you get started quickly.
Pro Supports multiple Y axes
Important for trend correlation, eg. comparing number of clicks to sale amounts. Not same scales / units.
Pro Library to support Microsoft .NET
Compatable with .NET framework 4+, can develop graphs from server side for ASP .NETand ASP .NET MVC applications.
Cons
Con Not actively developed
During 2016 was few updates, more updates in 2017
Con Spotty exporting
Exporting doesn't work well (if at all sometimes) with SVGs exported from anything other than Adobe products.
Con Weak documentation
Explanations provided in the documentation can often be unclear, with some features missing from the documentation all together.
Con Commercial
Highcharts is not free for commercial projects, with a starting price of US$590 for Single Developer + Maintenance & Support
Con The examples are not that great
For instance, example's JsFiddle may get stalled when loading.
