In 2006 the linux desktop was about the same as it is now, the Windows one was better. In 2006 I didn't have a smartphone yet. And in 2016, I don't have one any more.
(Actually I have one from work, but I only seem to use it as a wireless hotspot.)
But XP was very good for its time -- it brought in the big menus and (quasi?) full-screen stuff which later metastasied in Win 10. Though those menus were also a throwback to the good old DOS text-mode menu systems.
Win7 was of course another good one, a few years later. But note: the difference between Win7 and Vista was not the UI design -- it was the performance and other aspects of technical execution.
(Actually I have one from work, but I only seem to use it as a wireless hotspot.)