They also offer a solution that analyzes access logs, which is useful to capture traffic from ad-blocking users from your web server. As far as I understand it's not part of the open-source version though.

We run Matomo on a self-hosted server for all our websites and it works very well, there's a large discrepancy between the traffic / visitor count shown by Cloudflare and Matomo though: Matomo will show 50-80 % less unique visitors than Cloudflare, which seems a lot even when accounting for ad-blocking users. It might be due to our very user-friendly cookie script though, which only loads Matomo after the user explicitly clicks on OK (and he/she can click on "Decline" as well). Guess we should investigate how many people actually click on "Decline".

This won me over with their extensive API though not so modern but does the job. You can most definitely get the same data like GA.

Concur, pretty much can track everything GA does, with a much more straightforward interface

Yes, Matomo! Easy to use, and I love the fact that it's a self hosted solution.