This will be "unpopular opinion" it seems, but…

386 - Windows 3.11
486 - Windows 95
Pentium or newer - Windows 98

max out on RAM in all cases.

GemCookie wrote on 2025-08-14, 09:25:

I'll take Windows 95 on any hardware. Both operating systems are horribly unstable, but 95 at least runs significantly faster, even on a Pentium 4 system. I also have a soft spot for the underrated releases – I've skipped 32-bit Windows XP for 2000, XP x64 and Vista on several of my machines.

Echoing the sentiment, everyone already knows my opinion but here goes again anyway:

Windows 95 OSR2 up to something in the ~1 GHz range, always. Pentium 4/AthlonXP is where I tend to draw the line. On hardware older than that Windows 98/SE doesn't offer any tangible benefits, and is often less stable and slower, even with its supposedly improved memory management etc. In some instances you'll find drivers for things out-of-box in Win98 that you would have to manually add for Windows 95, but that's a minor issue - just have the drivers ready to go and its not a bother. You'll usually have to update the drivers shipping with the OS to newer versions anyway.

For P4/Athlon-era hardware, one might as well skip ahead to Windows XP - but there some people prefer Windows 98 because it allows them to keep "real DOS" for older apps and games.