Hi, that's pretty much the golden age of tinkering to me - lots of options from lots of manufacturers.
After all, that was the last platform that combined CPUs from Intel and AMD, then came Slot/Socket 1 and A, all with their own chipset.
Keep it simple. Try getting a major brand, if not even one that still exists and has customer service like manual and BIOS downloads. Asus, Gigabyte, MSI come to mind.
FIC, Soyo, Abit - probably all fine as well.
MMX 166 sounds just right, no need to contemplate alternatives. There was more advanced stuff around in '97, but real people bought just that.
What comes to mind, if you buy a used board from back then, there were those in 1997 with linear voltage regulators that just burn off the excess power in front of the socket.
And there were the slightly more modern ones with switching regulators.
You can tell the former by a big ass heat sink:
http://www.amoretro.de/wp-content/uploads/fic … vpx_chipset.jpg
And the latter by the one or two little coils next to the socket:
http://www.amoretro.de/wp-content/uploads/soy … _vx_chipset.jpg
Not much difference in practice, but the cleaner solution and probably more stable.
So, that puts the board safely in 1997, not earlier.
Chipsets, see the big-ass chip in the last pciture, that says "437VX"
https://en.wikipedia.org/wiki/List_of_Intel_c … entium_chipsets
The last three chipsets were known as HX, VX and TX.
They vary in features, but can't make much wrong with those.
Via VP/VPX chipset based like the former will also do fine.
The latter board has the longer, 168 pin RAM socket, besindes the older 72 pin ones. No difference in use, but modules, larger ones, are much easier to source. But, not much point in using more than 64 MB of RAM, so 4 x 16 MB of 72 pin ones will be easy to find.
Try getting a board with a button battery, like those I linked to. Long story.
Sound, VGA, a matter of faith. Nvidia Riva 128, Ati Rage something, S3 virge, 3DFX Voodoo in case of money.
Sound, if you want easy, Soundblaster anything. Cheap: ALS100 or ESS based, generic ISA card.