If you're looking for a distribution for an aging machine and you want to go with something other than a Ubuntu-based distribution, walk through the Arch with Omega.
PCWorld’s guide helps users navigate the overwhelming choice of approximately 250 Linux distributions by focusing on five main strains: Debian, Red Hat/Fedora, Arch, Slackware, and Gentoo.
From just learning to code to seasoned developers, these are your distros of choice.