I would counter that the AMD drivers are not great. I got a whitebox last year with a 5770, and the experience was terrible. The open source drivers couldn't do 3D acceleration properly, and the proprietary drivers refused to do dual-screen - the maximum available resolution across desktops was a square 1920x1920.

In my experience, nvidia has been providing a superior linux experience in the trenches for the past couple of years. The 'amd is good for linux' seems to be an emotion from yesteryear.