I guess im a bit odd, I have little interest in anything older than a Pentium, and my lack of interest isn't because of the CPUs.
Its the lack of integrated systems on the older systems that I simply have no desire to revisit, I have several Pentium class setups I can use that are capable of running at XT speeds if I really need to run software that old and if I really need to then I do have a SBC 386 that I could use. (Now that I think about it, I have no idea if it even still works)
I would make an exception here .. a monochrome amber or green XT would be nice to have around, same for a CGA/EGA 286, they are rather unique due to the display adaptor and you can certainly make a case for using one with software that doesnt support VGA/Protected Mode. But if the software does support VGA and will run on a 386/486 then really a socket 7 Pentium/K5/K6 would work just as well if not better while providing integrated IO and you can even slow these CPUs down by simply disabling cache.
Socket 370/462 to me are retro setups, I consider anything pre SATA to fit that name perfectly.