[Fyron]

Noone says you have to use Gnome with Ubuntu. There are a bunch of sub-distros with different default DEs (Kubuntu, Xubuntu, etc.). You can also just not install the Gnome package and install something else from apt when you do a custom install. The core of the OS is exactly identical between Ubuntu, Kubuntu and the rest. The only difference is putting in a different default DE package on the installer. They all use the same apt repository, and you can choose the DE of another from any of the base installers.

Pretty much every major distro (including Fedora, Debian, and Suse) has their default DE, with options to install others.

Personally I'd recommend staying far away from any distro without a robust apt repository (I'm looking at you, Fedora). RPM type systems are a real pain to work with, compared to the trivial ease of apt and its GUI offspring (aptitude, synaptic, etc.).

There really isn't much software available on one distro but not the others, beyond tools made specifically by the distro authors for that distro. Ubuntu has pretty much everything in its apt repository that Debian does.