The goal: a simple server to run some (lightweight) private services, for hardware i will be using a Raspberry Pi 4B. Primarily because it has GPIO pins which i can use for my other project, see Home sensor node.
It will run headless, without peripheral nor screen attached, and configured to be hands-off once set-up. To give an insight in the services (e.g. sensor data from Home sensor node) one could add a small display but in my case the device will not be placed in a visible spot so i use a web interface instead. I also wanted to avoid possible light pollution from the display’s backlight (alternatively, on could use an e-ink display). The Raspberry Pi will be running 24/7.
The used hardware is listed here, a Raspberry Pi 4GB + SSD. While the 8GB variant might be tempting, just because it exists, 4GB (even 2GB) should be more than enough for this use-case. More RAM might have slight performance advantages by keeping more swap and temporary files in memory; depending the workload type. In general over-provisioning does not make sense, by the time you would need the additional RAM a new iteration of the Raspberry Pi might be available which also brings a better CPU. Of course YMMV depending on what you are planning to do on your system.
First up, the operating system!