1. Voodoo2 - huge performance increase from Voodoo1, plus in SLI it was even faster and able to render in 1024x768. It was still a beast even after new generation was launched (V3, TNT2) and competitive even after another generation (V4, GF256).
2. 8800GTX - very big performance leap, could play games a long time, was launched at the end of 2006 and most of games ran fine on it in 2011-2012 (6 years later). Also first DX10 card.
3. GF3 - first DX8 card, fast, lasted quite a while
4. 9700 Pro - first DX9 card, fast, very good image quality
5. Voodoo1 - basically first solid 3D card, but unfortunately it only had 4 MB RAM (some had 6MB or even 8 MB, but the standard was 4 M<MB) and it was too slow compared to the next generaion, so very quickly new games weren't very playable on it.

Honorable mentions:

-Riva TNT: first 32 bit 3D chip (but with big performance penalty), also slower than Voodoo2 in most games (even if it was launched later)
-Geforce DDR: first DX7 card (T&L), but those features weren't used in games until much later, when it was too slow. Also not much faster than TNT2 Ultra.
-6800 Ultra: nice performance jump from previous generation, lasted quite a while...
-Voodoo Banshee: most people think that Banshee was a bad card, but it was cheap, had very good 2D quality, it supported high resolution (for that time), had good speed, it supported glide, opengl and d3d, it was the perfect card for gamers with a limited budget. Banshee paired with a K6-2 or a Celeron was a very good choice. imho.
-8800GT: very good price/performance ratio.
-6600GT: same as above, the first "mid" level card with very good performance

ASUS GeForce 3 Ti500 64 MB it's the best. Costed like a new car too.

From my perspective:

S3 Virge - You're all rolling your eyes, but think about this for a moment: Millions got their start down the path to 3D thanks to the S3 Virge and it's derivatives. Yes it was slower than CPU rendering, but visually nothing could compete with it as far as 3D images were concerned, not even the Voodoo 1 (this was stated in several magazine articles during the time). The Virge was everywhere, every 3rd party board manufacturer offered at least two Virge cards in their lineup, whitebox retailers had shelves loaded with Virge cards from companies like Jaton, and the respectable Number 9, who manufactured their own chipsets and cards, also manufactured and sold Virge based cards. I'd be surprised if anyone on this very board that owned a PC in the mid-late 90's DIDN'T own at least one Virge or Trio3D card (which is still a Virge, but rebranded to avoid the negative stigma and to extend S3's lifeline until the Savage 3 was ready).

Voodoo 1 - This was the card that made 3D pc gaming worth a damn. Yes there were other cards with decent performance, but once you got your grubby hands on a Voodoo card, you didn't leave the house. It made pretty much everything better and once the MiniGL was released, it was pretty much the defacto standard for anyone playing Quake/Quakeworld online in those days. Glide was THE API for gaming, D3D was a joke, and OpenGL wasn't supported by enough hardware to grab the market like it should have. Performance-wise it was pretty hard to beat the Voodoo1 and if you had the coin for it it would be impossible to beat if you were one of the few that bought one of the utterly insane Quantum 3D Obsidian 4440V single board SLI Voodoo cards.

Rendition Verite 1000/2x00 - The chipset that should have taken 3dFX's dominance away. Numerous issues plagued it's release but one gamed helped it along a bit: vQuake. iD created their first accelerated 3D port of Quake for the Rendition chipset using their Speedy3D API and the result was pretty damned good. The numerous problems with Rendition's release allowed 3Dfx to take the spotlight, thus relegating the Verite to second place status. It was still a rather useful card for older machines as it offloaded stuff like triangle setup from the CPU, so even P5's could have reasonable gaming speeds. My memory is a little fuzzy here, but I seem to remember the V2100 powered Diamond Stealth S220 being a part of the official reference gaming rig of the then fledgling Pro Gamer League along with an AMD K6 233 or something like that.

Nvidia Riva128/Riva128ZX - Nvidia had their own API at one point. The NV1 had it's own API and a few games were written for it, most notably Sega's Virtua Fighter and Toshinden. Nvidia learned from their mistakes with the NV1 and developed the Riva128 without it's own native API. This was, IIRC, the first chipset that focused on D3D and OpenGL for rendering and it showed. It was fast enough to be a competent alternative to the Voodoo cards of the day and being a single card solution was attractive to many.

Nvidia NV10/Geforce 256/Quadro - As others have said, this was the chipset that brought us to where we are today. Hardware T&L was strictly the realm of high end 3D workstation cards when the Geforce256 was released. It would be a few years before there was widespread adoption of T&L acceleration in games but the whole reason we have it today was because of the original Geforce. The "prosumer" variant, the Quadro, put excellent 3D features for applications like 3D Studio Max within the reach of many people struggling to get by on cards like the Permedia2/3, Number 9 T2R4, or even older Matrox Millenium II cards with a hefty, yet pricey 32MB RAM upgrade. Tests between the Geforce/Quadro and high end 3D cards from 3DLabs and the like were favorable considering the price difference AND it was found that all it took was to flash the bios with that of a Quadro and you could turn it into one, thus slowing it down a bit but gaining more accurate polygon rendering (important for CGI/CAD guys).