I have a i7 2700k 16 gig ram and 780ti but last I checked regular ubuntu it seemed bloated. I just want a simple OS with no bloat, I cant remember if it was K or X ubuntu I tried before and I liked. I want a similar interface to Windows i.e small taskbar at bottom which opens a program folder, whatever one I tried before I liked but was awkward to install programs that werent standard formats like emulators. I also noticed that despite my powerful pc ubuntu seems much faster.
Both KDE and Xfce desktops look similar to the Windows 7 user interface. KDE requires greater resources than Unity or Xfce. The lightest desktop available in the Ubuntu family lineup is Lubuntu, with the Lxde desktop. You may want to look at LXLE, an "Enhanced" spinoff of Lubuntu.