The VoodooІ chipset is available for some months now and still there is not much of a competitor to it yet. More and more manufacturers want to make money with it, maybe even more enthusiastic since the latest 3D chip review Tom has been doing revealed that there won't be any 3D outperforming a dual VoodooІ solution in the short term. The original from 3Dfx is still first choice since it offers great performance, no matter whether you use one or two VoodooІ boards. Moreover it is the most compatible 3D accelerator, uniquely supporting Direct3D as well as the very successful 3Dfx own Glide engine.
Buying a VoodooІ card only according to benchmark results would be almost small minded. I doubt that performance differences do originate in any way from optimizations of hardware configuration or drivers. The drivers are basically provided by 3Dfx, only the appearance in Windows and maybe some settings of advanced options are different between the manufacturers.
As you know VoodooІ cards use single cycle EDO memory at 100 MHz clock speed. Since the limits of EDO memory have been reached here, performance cannot be increased by clocking the memory even higher. If you do this anyway, you will earn wrong colors, wrong or missing textures or similar effects and even hang-ups. I think it's unnecessary to mention that you also risk your whole VoodooІ board which could end up dead easily.
The only way of obtaining higher performance is to overclock the VoodooІ chipset itself. The default clock speed is 90 MHz, nevertheless some manufacturers have their products running at up to 95 MHz by default. All drivers include the option to change the chip clock manually, only the Miro drivers warn that this could cause damage to your board. The different default clock speeds are the main reason for different benchmark results, so a recommendation has to be based on other factors: Does the card have TV outputs? How easy and comfortable are the installation and the drivers? What about the picture quality and the loop cable? Which software is bundled with the card? How temperature-sensitive is the card? Is overclocking possible?
I can provide one answer right now: the installation is not much of an effort. Since VoodooІ cards do not require an interrupt you may place them wherever you want. The software is also installed very quickly, either directly when Windows finds the new hardware during boot up or later on in the device manager. Some drivers (e.g. Miro, Hercules) have their own installation program.