I would argue that Windows 2000 was the last decent version of Windows. Fast, non-bloated, ran DirectX and games better than Windows 98 ever did, and as stable an operating system as I'd ever run.
win2k was my favorite. had a slipstream install with games i grinded and nothing else and it was the fastest desktop experience i've ever experienced to this day
And yet, Win98 (or ME if you consider that a working OS) was the last OS where there was no "system" account with higher privileges than the user. Win2000 was the first OS that gave me the "access denied" message.
I'm still looking for a desktop OS where user logs in as root/system and all the programs and services run as limited accounts.
I recall it booting more slowly than 98 or ME, but I don't recall it being obnoxiously bad. I do remember disabling a lot of services I didn't think I needed, though.
Back then (probably xp era) I remember quirks like needing to configure the IDE controllers so if you didn't have both connectors on the PATA cable used it would spend a ton of time trying to detect a device where there wasn't one. You needed to go into device manager and disable that connector (unless you added a drive)
It was much slower than current OSes. Windows 2000 initialized Windows Services in a serialized order which caused lengthy boot times, even for an OOTB copy.
XP changes this to a parallel + delayed service start up, but 7 and 8 really focused on boot times.
