I had a lot of issues with this game before, so much so that I only managed to finish it one year ago. Here's what I can tell about the drivers, if this helps.
The game has had issues with D3D driver for a long time now (from crashes to black letters/waterfalls etc). It was - really - annoying. People actually went for another driver, rOpenGL.
rOpenGL is, as far as I know, a not quite finished driver used before nGlide appearance, but isn't 100% ideal either (control stutter, and fog being too thick and hard to change, apart from a fix which gog.com may have included). But you can finish the game this way, I did and I think it was the most widely used for a long time. It's just that you will probably have to change settings here and there, according to the level.
And finally, nGlide came in, and saved the day! The Voodoo driver came with the last official patch, and with this tool the game is definetely playable, even if a bit blurry (depending on your nGlide settings, which you should tweak a bit indeed). Ah yes, in-game menus are blue, strangely, but it's fine. I literally wanted to play the game again when I discovered nGlide supported Severance, and I launched a new game... It appears to be the safest way to play - playing while understanding too late that fog is too thick, that gamma is too low or high, that your aim with a bow can stutter at the wrong moment... All this, gone with nGlide!
So, I really think you should go for gog's default 3DFx driver/nGlide, not because it's the prettiest driver (D3D was...), but simply because it's the best balance to play the game without adding technical oddities to your (personal) death count, while still enjoying the art and atmosphere.
In any case, thank you gog.com and have fun, it's worth your time!