24-Way AMD Radeon vs. NVIDIA GeForce Linux Graphics Card Comparison
Along with Unvanquished, Xonotic is another one of the most professional looking and quality open-source games.
Overall these results are largely in line with current expectations given the proprietary AMD Catalyst and NVIDIA graphics cards at the moment. I'm extremely curious to see how NVIDIA's Maxwell launch will go (stay tuned for NVIDIA Maxwell Linux benchmarks on Phoronix).