We'll respond shortly.
A team is migrating from PaperClip to CarrierWave and while the site seems to work fine, however tests are failing in strange ways. Specifically, tests about replacing images aren’t saving any changes to the database, but there are no validation errors.
The easy recommendation was HighCharts (http://www.highcharts.com/)
And there is also D3 (http://mbostock.github.com/d3/) but it is much more low level