I honestly don’t care much about the specific library you choose. I care about the API designed for it and how easy it is to style.
I’ve written a lot of charts for projects, and typically have used Highcharts due to uniformity with other company assets. The Highcharts license is a major problem though, its not free for commercial use.
I care that a chart component would allow only primarily simple charts. On mobile, you don’t usually want/need a crazy amount of data on the chart. If you do, then don’t use the built in chart component.
<ion-chart title="ION Stock Price" x-axis-label="Date" y-axis-label="Price and Volume">
<ion-chart-series data="series1" type="line"></ion-chart-series>
<ion-chart-series data="series2" type="bar"></ion-chart-series>
$scope.series1 = [...];
$scope.series2 = [...];