Because it basically does everything you could want, with excellent DOS compatibility, great image quality, and good 3d with glide support. They are also fairly common, although the PCI versions are a bit harder to find . The only real issue beyond the price is that they run pretty hot, so you need to be careful and make sure they are getting cooled properly. I still prefer the Voodoo 5, but that is getting expensive and hard to find, especially the PCI version.

Thanks for your answers, I have decided to go with the GeForce 2 MX400 for the time bing (mainly due to the fact that it costs a tenth of Voodoo 3's price nowadays)

Back then I had a V2 and a good enough graphics card (don't remember) so a V3 didn't make sense to me when it came out.