NT 4.0 was solid and felt fast! The UI was so snappy. You could just leave it running and never reboot -- it almost became a geek humble brag to do so. For those too young to remember, one of Windows 98's marketed features was the ability to use ACPI to turn off your computer without you having to press a physical power button! It was just expected the device would need to be turned off.

Windows 2000 was great too, which PC enthusiasts at the time realized was essentially "NT 5.0 but can play games because it has (official) DirectX". It's amazing how there's so little nostalgia for these two OSes. I watch some retro PC YouTubers and most haven't ever covered them. There's so much nostalgia for Windows XP. But among enthusiasts, the first impressions were that it ran slower than Windows 2000 and looked like a Fisher Price toy. I think a lot of PC enthusiasts hung onto these two OSes, as you point out, until they eventually relented and used Windows XP around the time of Service Pack 2's release.

I ran LiteStep (http://litestep.net) on NT 4.0 at one point in my teens, completely unaware that Apple would eventually make a NeXT-style operating system something I'd use as a daily driver.