VOODOO 1 - this is without question. If you think its one of the more recent cards, you either havent been around long enough to appreciate it, or you arent looking at the question correctly. Cards like the Geforce/V3 etc are indeed great cards, but its a matter of comparing it to what was available BEFORE its existance. Take the Geforce GTS, well, is it really that groundbreaking compared to the Geforce DDR? Nah, not really. Fast, but side by side, not really that big a deal, probably couldnt tell just looking at them... Now, look at what was available when the Voodoo was released... ATI rage?!?!? gimme a break. The one card that you can mention in the same breath it the first Matrox card that ran OpenGL, the Mystique (i think?) I guess it was out the door a week or two earlier, but never really took off, or was responsible for the 3D explosion. Voodoo2 was also the shiznit, but, again, was nothing too groundbreaking compared to the Voodoo1, just faster.
I still remember the first time a saw QuakeGL fired up, and I nearly wet myself, and there is NOTHING that has happened THAT IMPRESSIVE since, only steps...
IMHO
*EDIT - my bad, i was answering the age old 'what is the greatest card ever...' question. I always let those go and dont answer, and in my zeal, replaced 'favorite' with 'greatest'. Your favorite is your favorite, my answer is the 'greatest' !!!
Oak