I went from 95a to 98SE(hated it), to Windows 2000 SP1(loved it). I've actually liked it less since SP2,3&4.
Don't like XP, too many reasons to get into it. I could rant for hours. I am forced to use it and newer... nuff said.
Vista is just as bad! I have yet to try Windows 7, but I don't like what I've seen.