I didn't mind Win '98, but it was a little bland and I needed to change the colour and wallpaper regularly to stop getting bored with it. However, after a while of using '98 discovered MSStyles, which changed the UI and desktop icons.
That was fine for a while, but then I discovered XP and Windowblinds. Since then I have tried Vista; Win 7; Win 8; Win 8.1 and Win 10. Of them all I liked Win 7 and Win 8.1 the best.
Win 10 is supposedly the greatest OS that MS have ever released, well according to MS it is, but I'm not overly fond of it and hope that MS changes its mind about forced updates and its data collection policies. When that happens Win 10 may be passable.