Matomo can be installed on its own server, or you can use Matomo's cloud service. Regardless, you own your own data, unlike for example Google Analytics, where the data is saved in Google's environments.
You're probably aware of the Schrems II ruling, which meant that it is no longer permitted to send personal data to the United States with reference to the Privacy Shield. With Matomo, you can feel at ease that you yourself control where the data is to be saved and that it is not collected via the USA.
Because you control the data in Matomo, you do not have to deal with sampling, as in Google Analytics. Here you can trust that you always see 100% of the data collected in reports.
In Google Analytics, tracking a visit is interrupted if it has generated more than 500 hits (packets of data sent). Such a restriction does not exist in Matomo.
Matomo supports sending up to 50 custom dimensions with a minor rewrite in the database. This can be compared to Google Analytics which only allows 20 if you do not use the paid version (200).
Unlike Google Analytics, Matomo may collect personal data, provided that you have first obtained consent from the visitors. This is well suited for closed systems such as intranets.
If you have accidentally collected personal information, you can easily delete it with Matomo. As you have access to the database yourself, you can delete the individual task.
Matomo allows tracking without cookies. This of course means that you can not link a user's different visits, but the advantage is that you do not even have to display a cookie banner on the website.
Because Matomo collects data in a database you control yourself, it is very easy to connect data from Matomo to its own data warehouse, visualization tool or other BI tools.