My favorite version of Windows is Windows 2000. I think it was the version of the greatest quality and the best interface. The worst Windows version in all respects is Windows 7.
I know of no interface-affecting bugs in Windows 2000 even though I used it for years. After that Windows started to degrade and lose in quality. I know some 10+ bugs and glitches in XP, some very annoying. I never tried Vista but they actually handicapped the Windows Explorer in this version. In Windows 7 they continued the destruction. I think Windows 7 was definitely the worst Windows version ever both in terms of quality and inteface. I know many tens of bugs in Win 7 which all pop up just after you start using the system. It ended its life on my PC after it failed to boot after a regular update.
Windows 8 is marginally better than Windows 7 with all the tweaking and if not to count the "Modern/Metro" apps and interface. I haven't looked at Win10 yet, but I think it may be even worse than Win7.
In terms of change compared to the prevuous version, Windows 95 was definitely genial and brought the most features ever. My first Windows version was Windows 3.1.
Win 95 - epic improvement
Win 98 - minor improvements but also some unpleasant changes
Win 2000 - huge improvement
Win XP - some degradation, minor improvements
Win Vista - major degradation, the only improvement is better icon theme
Win 7 - further very serious degradation in all respects, close to catastrophe
Win 8 - small improvements, better quality than Win 7, but handicapped with "Metro"