Have you used recent versions of KDE (on openSUSE, for example) or GNOME (on Fedora)? Because Ubuntu (or Unity, to be more precise) did not really change since 12.04 and largerly used GNOME applications anyway. The things you actually can attribute to Ubuntu, for example the Software Center, are an absolute trainwreck in comparison to the "competitors" (GNOME Software e.g. is moving fast and is capable of staging upgrades to the next OS release as of recent).
