Recs.
Updated
Debian is composed of free software mostly carrying the GNU General Public License. The operating system is developed by an internet collaboration of volunteers aligned with The Debian Project.
SpecsUpdate
Pros
Cons
Con No choices
Debian basically doesn't give you any choices, even dpkg supports this feature with virtual packages: for example, it is very hard to use a different sound system than ALSA, like OSS4 or to use ALSA with pulse audio emulation, and the same goes for different init systems.
Con Ridiculous package splitting
Even though it makes sense to split devel and the actual binary of an application, the splitting has become as mess in debian and its derivates: for example the nvidia driver is splitted into over 40 different packages: https://packages.debian.org/en/source/sid/nvidia-graphics-drivers
Con Stable release contains extremely outdated packages
If you want the newest packages, you'll have to do a minimal installation of Debian stable then upgrade to testing or you need to install testing directly: https://wiki.debian.org/DebianTesting.
Con No good choices of fresh desktop environments
GNOME is quite outdated and buggy;
KDE is too old, even in Sid it is at 5.14 branch (at Jun 13 2019 Plasma 5.16 is available in many rolling/fresh distros);
XFCE behaves like crooked, visual artifacts at the taskbar and so on;
Cinnamon as far as I know works better in Linux Mint compared to (almost) any other distro;
For other desktop environments (e.g. MATE) can't say - these are too new (as projects) and possibly incomplete, thus might have many bugs.