Unity provides best UX on Linux so far, or have other desktops catched on? Last time I checked Cinnamon (tried it on Arch Linux though) and Gnome Shell both lacked the depth of design compared to Unity.
(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