As a programmer, I find Fedora with the Gnome Classic theme and the No Topleft Hot Corner extension[0] to be an excellent, clean, effective desktop UI. But in order to get this working properly, I had to go through package hell for a few hours to get the right graphics drivers and tweak a bunch of settings. I've heard Linux Mint is good for non-programmers, but I've never tried. Unity in Ubuntu is the worst desktop experience out of all I've tried.
[0] https://extensions.gnome.org/extension/118/no-topleft-hot-co...