Currently the best 3d quality is available on 2d/3d cards such the riva tnt or the matrox g200. The image quality beats any currently available 3d only add on card. The matrox card is slower, but is still a good card.
The riva tnt currently matches or beats the speed of a voodoo2 based 3d add on card, with higher resolutions and better image quality. In some instances (especially in direct 3d) the riva tnt passes dual voodoo2 cards in sli mode.
Your best bet right now is to go with a 2d/3d card, but get a really good one such as the riva tnt (if your system will support it). 3d add on cards work really well, but for the additional money, they are just not worth it anymore, when you compare them to the new chips out there. The only way I would say to get a 3d add on card would be if you have alot of games that run glide. But even then, the Banshee would be a good alternative. If glide is very important to you, get a voodoo2 or banshee (the banshee if you want a 2d/3d card).
Voodoo1 or Voodoo2 add on boards are only a
really good choice if u have already a fast 2D Card but it's not as fast in 3D as u which. So u can get these boards as an alternative to a compleate new Video Card.
If u want to buy a new card and if you decide to take your old Video Card out of you system, buy an 2D / 3D Card.
(with Riva TNT, Banshee, Savage3D or G200)
But remember: don't buy a fast card if u have still a slow processor.
In that case, older Cards may get similar frames but tey cost only about the half !!!
Only a PII or K6 / K6-2 faster than 266 Mhz will really take much advantage out of your Riva TNT board.
I have seen many people saying that you really need a 400Mhz+ CPU to take even CLOSE to full advantage of a TNT. Even going up to a celeron 450A gives you more performance.
Anyway back to your original question. In Australia (aka arse end of the world according to a FORMER prime minister) the TNT is cheaper than a Voodoo2, and it does both 2D and 3D. If you're buying a new computer or upgrading and need both 2D and 3D cards, get a combined card. You eliminate the pass-through cable as well, which is said to cause a loss of quality.
If money is important to you, get one of the few months older chipset boards, like the intel i740 chipset boards. These boards are not screamers, but have way better image quality and drivers than the savage 3d based boards. The image quality for the savage 3d based boards is currently worse than a voodoo2/banshee based board, similar quality to a riva 128. The images are are too dithered. You should be able to find a good 8mb i740 board for a price better than the savage 3d. Unless frame rates are the most important thing for you along with price, dont get a savage 3d based board, atleast untill they fix their driver problems. Remember, anything above 24fps is not needed, you cannot see past that rate. Currently, I feel image quality is a higher concern than having a card that can pump out 100+fps.
I would rather be looking at an image in high quality, high resolution at 35fps than an image that is lower quality and lower resolution at 80fps.
According to my I-like-to-speak-though-my-arse friend, the human eye can actually detect refresh rates up to 60Hz. Apparently there IS a difference between 35fps to 60fps, but in the middle of a deathmatch you would not be noticing the difference! 24fps is about the bare minimum for smoothness, I think setting a minimum of 30fps (using a timedemo like massive1) is a good idea just to make sure you're silky smooth. I agree though, there's not a lot of point in pumping out 120fps and being proud of it. Unfortunately there are types (such as my afore-mentioned friend) who consider their framerate an extension of their (putting it as subtly as possible) "masculinity". He's determined to go for the "ultimate in speed" which sounds like a bit of a wank really, basically he wants a V2 SLI setup that cranks out 105472957295732 fps just so he can look good. He's also determined to stick his computer in a fridge so he can make it go faster. Go figure. What were we talking about anyway? strayed from the original question that's for sure.
At any rate I agree with you, I'll be setting my card for the maximum resolution that still gives me a bare minimum of 30fps. As long as it's above 30 it'll be beautifully smooth, after that point the quality matters more to me.
To risk answering the original question, I suggest you go to http://www.riva3d.com/TNTV2.html
It gives a whole bunch of images comparing the V2 with the TNT. There is a little thing in one of the corners saying "V2" or "TNT", it took me a few seconds to realise that, otherwise you don't know what the hell they're talking about. there's one pic there off a V2 that looks like it's being viewed through a layer of snot, you'll see what I mean when you go to the page. The TNT has clearly better image quality, but the V2 is crying out for its gamma to be turned down a touch.