S3 has very extensive support with third party utilities. Rage doesn't, but usually has better image quality, because they were mostly manufactured for ATi with strict quality control.

As a fellow DOS fan, I say put the S3 in the 486DX2; it's compatibility cannot be beat. And put the Banshee in the P3 for late DOS games.

Check out this lovely compatibility matrix: https://gona.mactar.hu/DOS_TESTS/

The 3D part of the Rage does nothing for you until there's a couple of hundred Mhz behind it. The 2D part is close to being a Mach64 though, but mainly any advantage is to windows resolutions not DOS. S3s are very DOS compatible. Personally I'd go with the S3Trio in a DX2... stretching for early 3D accelerated stuff, you really need a DX4 or better and a card that early undemanding 3D accelerated games supported like the Virge. IDK if it's worth stretching for the first voodoo games with the Banshee in a 486 because Voodoo1 games can be problematic to get working on later Voodoo, then the number that do anything but slideshow on dx2 will be pretty low too, so unless the stars align and there's "that one game" that happens to fall in the Venn diagram cross of "not totally sucking on a 486" and "works on later voodoos" then the Banshee will be better off in a system that gives it more range.

Can't wait to get this baby on Friday!
Gainward Dragon 4000

Green PCI 16MB Voodoo Banshee

Even though I have a Slot 1 600Mhz with V2 SLI and Slot 1Ghz with a V3 2000 found myself playing NFS4 on the Slot A 650Mhz PC with a Banshee. Game play was fine. Poor old Banshee doesn't get the respect it deserves.
Sure it has its limits but they don't deserve the outright dismissal they seem to get from most

I saw a benchie once where the banshee just edged out a Voodoo 3.. they are kinda "all over the place" though, benching near V2 or near V3 depending. All in all though a pretty solid choice for those middle mhz machines between MMX and the magic 1G