I really like chart.js

http://www.chartjs.org/docs/latest/

Google Charts is an option I use a lot - surprised more people don't know about it. Maybe just because it was developed before the hip new land of React? (A bunch of react wrappers exist for it though)

https://developers.google.com/chart/

In addition to the alternatives already mentioned I really like https://frappe.io/charts

What the other replies said.

HighCharts for paid, Chart.js for open source.

AmCharts