Just to troll a little-- the "prettiest or the most modern" comment leads me to believe you're arguing for desktop applications which get installed to the OS as opposed to applications which run in the browser. But I find browser apps as accessed on the desktop to be prettier, more modern, easier to discover, easier to install/re-install/remove, more accessible, and vastly easier for collaboration, than the native applications written for a given platform. On the desktop they run much faster than on mobile. And the thing is plugged directly into the wall so you don't have to worry about battery drain.
(The one caveat to this being audio/video/3d creation-- for most of that you still need proprietary native applications for workable and stable UX.)
I'd really like some kind of Linux distro that boots me straight into Firefox's most stable auto-upgrading release, then have some keyboard shortcut to gracefully degrade down to xfce Debian or whatever for everything else. Perhaps with a default dialog:
"Warning: you are about to drop down to a Debian box. Refresh Button, Back Button, Touchpad, Audio, Wireless, and Fonts will all be set to Frustration Mode. Ok?"