When it comes to server operating systems (this is valid also for client O.S., but let's stick to servers not to be off topic), there are three main pillars: trust, stability and understanding.

Trust: my operating system must do what i expect it to do, when i expect it to do. I need to trust my server at all times to behave like i want it to.

Stability: my operating system must not crash or behave erratically at any time. Of course no software is bug free, but simpler or less-encroached operating systems provide reduced surface for bugs. At the same time, i should prefer a well-proven O.S. for the task at hand.

Understanding: i need to be able to understand why stuff happens, not just workaround quirks because they cannot be investigated.

In my opinion, the only viable solution on which you can build is Linux. It's pretty stable, itìs a de-facto industry standard on the server market, it can be trusted to perform how you want due to the very high level of control you have on it, and it can be understood troughly, which does not mean you might understand it, but you can if you want.

The same cannot be presumed for other, commercial, operating systems where more often than not updates will push on you unwanted features, crash unexpectedly, and cannot be understood fully because the source code is not available.

There are more Linux distributions out there than stars in the sky.

While, maybe, not technically true, it really feels like it is. Whatever your likings are, you will find your kink in the Linux distributions world. There are immutable distros, commercial ones, some are targeted to servers only, some are for media-servers, whatever.

I am an old-time Gentoo Linux user, i feel at home with Gentoo but, more importantly Gentoo offers some advanced points that i fnd well suited for the task at hand:

• You build it yourself, you know exactly any piece of software installed
• It can be as barebone as you need. Really barebone. Less attack surface. (more secure)
• It can be fully headless, good for servers (more secure)
• It doesnt force any design decision on you. Prefer OpenRC to SystemD? Perfect choice. Also true preferring SystemD over OpenRC.
• There is tons of good wikis and resources. A tad bit less than Arch Linux maybe, who knows.

When installing Gentoo Linux you have the total freedom to choose any single piece of the system, including whether to install or not a Cron Daemon and even a logger daemon. No other distro gives you so much freedom. Moreover, while you can use SystemD and NetworkManager with Gentoo, you are not forced to use them, and in fact specially for small servers, they might both be unneeded.