This is what it boils down to:
intel: good history of open source drivers available when hardware is released "enablement"
amd: recent history of providing some documents/support but limited resources/employees
nvidia: complete refusal to support anything but their proprietary driver
intel: intel/community created open source drivers only (lotsa docs/help)
amd: proprietary + community created open drivers available (with docs/help)
nvidia: proprietary + reverse engineered drivers(without docs/help)
As it relates to gnu/linux, the goal is "enablement" of hardware on release with distros available at the time. Distros can't legally be distributed with the proprietary drivers, it violates the licenses (but you can always download/install them seperately on your own). This is a matter of inconvenience for many and serves to undermine the proliferation of gnu/linux, not to mention making the job of the programmers harder as they have to essentially reverse engineer hardware to create drivers. (IE: what happens if I read/write a few bytes to X/Y, why didn't they just tell me this !?).
The argument of nvidia vs. amd's proprietary drivers is not at all what this is about. That would be better served in it's own thread. Intel doesn't even provide proprietary drivers and their hardware is amoung the best/earliest supported in linux.
I've used gnu/linux for nearly 15yrs now, and I grow to like it more each year.
I havn't installed windows or played the latest/greatest video game since 2004.
I'm very "niche" and wouldn't have it any other way