Matomo is also dead-simple to develop plugins for. So if you're looking at a product that can be customized beyond simple analytics, Matomo is a great choice.

Matomo is also dead-simple to develop plugins for. So if you're looking at a product that can be customized beyond simple analytics, Matomo is a great choice. I also used it a lot back when it was Piwik and the biggest issue was that it is backed by a MySQL database, and the way the reporting engine was designed meant that it would get pretty slow to work with custom date ranges with large volumes of data. But it did support caching and would pre-build reports over certain date ranges (by day, by month, by week, MtD, YtD).