I must've looked at this years ago, but for whatever reason, hitched my wagon to Chart.js and haven't really needed anything it couldn't do. And that's for weird one-off custom stuff. For business analytics I just self-host a Metabase server. I wish there were more visualization options with Metabase, but it's such a cinch to set up models and queries. But I don't often get a visualization request that justifies the time to create a custom chart.