* Windows Phone. Fantastic UI, and coupled with the Lumia, it was an awesome user experience.
* The old Winamp, with all the intricate shortcuts that I had memorized.
* Windows XP itself. I have been on Linux for years, and XP was the last Windows I used alongside it (for MSOffice). XP had reached the peak in terms of being able to control the desktop using the keyboard. And then the downslide started.
I know a lot of people who loved Windows XP, but I always hated it. Especially compared to Ubuntu, it felt like the past. Having to hunt down drivers and install them before any hardware started working was a pain, and after I tried Ubuntu and it auto-detected my wifi card and sound card, that was the end of any respect I had for Windows XP. And that's not even mentioning the number of times I had to call the phone number and read my license key to the robot to get my activation to work.
It wasn't until Vista came out before I could go back to Windows and not feel like I was taking a step backwards in time.
Well, people who like XP and older versions of Windows in general tend to like the UI, not the kernel :-P. I know many who would love a version of Windows 2000, XP or 7 (depends on the taste) with the Windows 10 kernel.
It is a problem with Windows that you have to take all of it or nothing. At least on Linux you can use whatever UI you want with the latest kernel.
* The old Winamp, with all the intricate shortcuts that I had memorized.
* Windows XP itself. I have been on Linux for years, and XP was the last Windows I used alongside it (for MSOffice). XP had reached the peak in terms of being able to control the desktop using the keyboard. And then the downslide started.