Debian is a popular choice, as is Ubuntu Server LTS. I've chosen Ubuntu Server LTS as my base. It's a nice compromise between the rock solid stability of Debian, whilst allowing for some more recent sofftware package releases in the repositories.
If you'd like to dive in more as a newbie to self hosted docker containers for personal software, check out https://docs.linuxserver.io/general/containers-101/
These guys package popular software projects in a reliable format, and they have some good guides to get started.