Earlier quoted context omitted.
Care to elaborate? Nvidia used to be the only discrete GPU manufacturer that had Linux support worth mentioning. I know that AMD/ATi has made a lot of progress, but is Nvidia really the worst at this point?
I believe nVidia is the only major GPU manufacturer left without full-featured open-source drivers. nVidia was once the best GPU manufacturer for Linux on PCs but they proved unable to make the leap from proprietary drivers to OEM-supported open source; Nouveau exists as a community effort but remains well behind the AMD/Intel equivalents. IMHO, assuming you get to choose your GPU, the only reason to mess around with…
On the driver side, a lot of the features and performance advantages of Nvidia cards are rumored to be largely implemented in software. (Think of things like having a really good optimizing compiler for shaders.) Open sourcing that code would allow other brands to copy a lot of their techniques.
On the application side, Nvidia produces a lot of developer tools (like CUDA) that are either tied to or heavily optimised for Nvidia hardware.
All this means that Open Source is largely antithetical to the way they do business.
OTOH, ATI Linux drivers went through a very rough patch when ATI decided that Open Source meant, "Hey, we can get a bunch of suckers to write drivers for us!" Everyone involved seems to have actually come out the other side stronger for the experience, and I'm very optimistic about their future.
That said, my understanding is that you are committed to Linux, you still get a more robust OpenGL implementation (ATI used to be buggy as sin) and better shader performance with Nvidia hardware/software. The situation is changing rapidly, and I would love to know if the information at the start of this paragraph is out of date.
Now that I've provided an infomercial for Nvidia: I'm willing to defend Nvidia's products, but I'm not really ready to defend Nvidia the company. Even if Nvidia's hardware beats the competition on all the benchmarks relevant to your use case, it's entirely reasonable to prefer choosing a company that is more willing to play nice with the greater community.