As I wrote I still do consider keyboard UI on windows the best, because it's AFAIK the only widely supported destop OS with full keyboard control of the GUI. But the Ribbons are not for me - it's a menu system that's also trying to be a context aware palette, which makes it worse than either a classic menu (easy to skim though and find what you want, especially on MacOS) or a palette (can be placed wherever it's the most useful, i.e. allowing the shortest mouse travel).

Please note that I still do consider Windows Office the best version nevertheless, but for different reasons.