Everyone knows that in general, Nvidia has the best supported graphics cards under Linux. But I don't want to buy into Nvidia's proprietary drivers if I don't have to. ATI has open source drivers, but they have almost no support, and their open source drivers are significantly worse than their closed source drivers. Intel has open source drivers, but their graphics are all integrated and built into the motherboard.
Are there any graphics card manufacturers which have open source drivers and are actually friendly with the open source community? I would gladly like to purchase from them if they exist.