As someone who ran Ubuntu server for a few years before moving to Debian. I would recommend Debian over Ubuntu just because I have had to do less maintenance with it. When I was on Ubuntu updating it was a constant concern of “will something change that is bad” for example they pushed the kernel live patch and the Ubuntu subscription banner as an update instead of an upgrade, so I updated as normal, and there it was.

I dislike OS’s that install new packages as part of their update procedures (an update that installs a new package instead of replacing an existing one should be reserved for upgrades), and Debian has never done that with me, so Debian is where I stay.