I can't seem to find much recent discussion on this since the release of OpenGL 4.1

I would like to know if Nvidia still has the upper-hand on Linux drivers and OpenGL support or if AMD is now the way to go.
Currently I run Mint Debian with dual AMD 4850's in crossfire. I don't have a lot of issues, however I am looking at an upgrade. All I care about is Linux/OpenGL support and performance of the proprietary drivers in the current top line of Graphics Cards.

I also can't seem to find any reviews or comparisons (they all seem to be about the open source drivers) on the Phoronix site as of this year.