You don't want the STB card with the Alliance chip, that chip left a bad taste after experiencing its 2D performance on the Voodoo Rush. The Mach64 is a safe card and a lot of people here have used it plus it can play a number of games that uses ATI's api (see list here on forums). The Trident card will get you the basics as always but don't know how well it performs.

I can't remember wich exact model. What you want to look for is probably an S3 variant.
If I recall correct. You need the S3 trio 64 or something like that.
There are a lot of discussions here on Vogons, regarding S3 cards and compatibility.

Avoid ISA cards. They belong to 286/386/early 486 systems. Even a high-end one can't compete with some cheapo Virge.

Btw any half-decent PCI card would work for you. A Trio64/Virge is a nice match for that PC, and so is the Mach64, but if you don't care about period correctness you can broaden your searches to GeForce MX PCI cards (2 or 4, doesn't really matter), as they provide great DOS performance and compatibility.

I'd say a Virge card like the one mentioned above or a riva128 , both work wonders for DOS.