Customisability & administration
Mould them to your liking.
When it comes to tweaking the installation, Debian, Fedora and Ubuntu rely on tools from the Gnome desktop, primarily the Gnome Settings for configuring installation. Besides this, the distros offer a different set of tools. For instance, Debian ships with Extensions Manager and Gnome Tweaks Tool, while Fedora has the Connections remote desktop client. Ubuntu has tweaked the Software & Updates app to let you easily enable additional repos and manage proprietary drivers.
The other two distros are diametrically opposite to each other. Slackware adheres to the Keep It Simple, Stupid (KISS) design philosophy, adored by advanced users who bank on it to build their installation exactly as per their requirements. Everything in the distro, from its installer to the package management system, is a reflection of its ethos of simplicity, though it comes at the price of usability. This means that although there’s no aspect of the distro that you can’t tweak and customise, it usually requires hand-editing text files, so customisability is inaccessible to many.
On the opposite end of the spectrum you have OpenSUSE and its YaST (Yet another Setup Tool) setup and configuration tool that handles everything from installing the distro to administering it. You can use it for things such as hardware setup, network configuration, controlling system services, tuning security settings and lots more.
Best of all, YaST can also be used from the terminal, which helps administer computers remotely via SSH, or in case you can’t boot into the graphical desktop.