If you are asking about what's the next best kind of video card, I will have to say Nvidia's Geforce series.
Geforce 1 is probably not too much of a jump of performance from Voodoo 3, but Geforce 2 MX or Geforce 2 is much better than voodoo3. ATI's radeon 7500 or so is also really good video card too.
But if you are interested in cards all the way on the top in terms of performance, Geforce 3 and ATI's radeon 8500 are extremely expensive, and not too much software are capable to take full advantage of them just yet. And of course, there are custom made cards where you can tell the companies whatever you want on them...
Of course, there's always voodoo5... 5>3... Bigger number should always means better, right... ?
If you care enough to buy a Geforce 2, I would gladly send you a PM about a great place with cheap price!