A rarity: most the posts on this thread seem right on.
I have a couple of G400 MAXs, a G450 PCI, Radeon VIVO, Geforce2 Ultra, and Voodoo5. I tried a Leadtek Ti 500 for 6 hours and gave up (unstable in my system).
The Matrox has the best DEFAULT color saturation and vibrancy, both in 2D and 3D. Sharpness is maybe a tad less than the Radeon.
However with the Geforce Ti, they have bumped up the default color and vibrancy close to the Matrox, plus you can use Digital Vibrance Control to bump it up even further, but this is overkill. I don't know if they did this starting with the Geforce3 series, since I've never seen that card, but the default Ti colors in 2D and 3D look more vibrant than the Geforce2 Ultra. 'Course I can bump the desktop brightness, gamma, and contrast to look just as good.
However for 2D sharpness, contrast, and clarity, you still can't beat the Matrox cards. The Leadtek Ti 500 is nowhere near as good, and I was told the FS card had special RF filters in it. The Leadtek still has a bit of ghosting at 1600x1200. I would say the order is this as far as 2D: G400 MAX, G450/550, Radeon VIVO, Voodoo5, Ti 500, and the non-Hercules Geforce2s are way back. Maybe the Ti 500 is on a par with the Voodoo5, but the Voodoo5 has no ghosting problem.
BTW, I have two Hercules Geforce2 cards and the 2D color and contrast is very very acceptable, using Detonators 11.0 and after. The 2D is really not half bad at 1600x1200, considering the speed of the Ultra. I am getting the Asus 8200-T5 Ti 500 when the price drops a little, only because of all the features. I don't expect the 2D at 1600x1200 to be that good. Otherwise I'd opt for the Hercules, assuming the 2D will at least be as good as on their Geforce2 cards. However the Hercules cards are priced at a premium.
I having seen any Gainward cards so I don't know if they are as good as people say. Some people have also knocked the Hercules 2D. But I run all these cards on the same monitor, a Nokia 446XPro. I think the quality of a monitor has a lot to do with 2D quality when you get to 1600x1200.