Whoa - Win98 is what Win95 should have been, and XP is what 2000 should have been, IMHO.
But Win98 is what a lot of folks stuck with as "working", in the same way as most people are sticking with XP instead of Vista.
WinME was a 16-bit evolution that was neither useful nor wanted. Vista is looking sadly similar in the 32-bit world - even though there are 64-bit versions. But then there's a 64-bit versions of XP, so the point is...?
So If you had said "Win ME and Vista" I'd agree!
Well, SD, I brought up 98 as since it was rushed and so fouled up they had to release a new version of it (Win98SE). XP was rushed, and we know the issues it had. Vista, unless you have the "right" hardware, is a pain.
Win2k was good, I liked that. It was nice and stable and would cause hardly any issues so how they made such a howler with they morphed that into XP is beyond me.
I deliberately ignored WinME. The less we are reminded of that the better.