Arch, because I've always had a better experience with it than Ubuntu, be it server or desktop. I also daily drive it on my desktops.
It's so much easier to setup. Only with Docker and MergerFS it's a command and easily updatable, instead of the PPA setups or bash installs you have to do on Ubuntu. The wiki is still the best.
And it's way easier to maintain when there's less stuff.
I used to regularly backup my photos to an external drive, but it'd still be in my house. Recently I just opened a cold object storage bucket at OVH and rclone to it every night. So even if they fail, the chance they fail at the same time as I do is pretty minimal. And I pay like 0.75€ a month for ~400GB