Upgrading from mysql 5.7 on FreeBSD to mariadb or MySQL8 I am looking into upgrading some major components of a webserver (php, apache, mysql).

I've done the update to 5.7 from 5.6. I've updated to php7.3.

What I wonder now is: I see that a mysql community edition is available (version 8). After a first install it failed to start so I rolled back to 5.7.
Now I'm wondering if it's worth the trouble migrating to mysql8 or even if I better would update to mariadb. And in the latter: which version of mariadb would I use or which one corresponds with mysql5.7 which I currently have installed.

Is mariadb/mysql8 stable?

For clarity. This is a production server. I'm not looking for new fancy features. But perhaps some more recent versions have better performance.

Thanks a lot in advance!
Any version declared "GA" is "good".

5.7 is only one major version behind what Oracle is providing.  There have been a lot of improvements in 8.0, but, as with any upgrade, you may or may not be affected.

MariaDB 10.3 is a good parallel to 5.7, but there could be differences -- in features and in Optimizations.

It is good that you are eager to upgrade, but since you had troubles with 8.0, I think it is reasonable to stay with 5.7 for a while.  (Some people are struggling with upgrading from 5.5 or even older versions!)