apt-get install lubuntu-desktop(I and many others really prefer kde3/4, gnome 2 (and even 3) as well as mate and cinnamon and some light weight wms over Unity)
On the other hand KDE is much more versatile and perceptive of user's choice. It has a rich set of software which includes a full productivity suite of KDE PIM (personal information management) and all Qt apps fit pretty well in KDE. KDE heavily uses widgets which makes your overall experience better.
You should give OpenSUSE 13.1 or Fedora 20 KDE a try.
> best UX on Linux so far
surely you jest
That said, Debian works perfectly fine for me on my phone. It runs lxde chrooted in userspace (Android is the booted OS), and I have no trouble using and operating Debian as far as things are available for ARM. Even compiling new things for ARM is usually no issue, though things like compiling Firefox are probably beyond what I would want to try on my phone :P
They are testing xfce as the default - http://anonscm.debian.org/gitweb/?p=tasksel/tasksel.git;a=co...
I've switched to xfce4. Gnome3 is crashy and glitchy for me, although I do like some of the UI tweaks.