Testing by an independent third party on a selection of AMD and Nvidia gaming class and workstation class graphics cards has found that AMD's drivers suffer fewer crashes while running the test suite, leading them to claim that AMD's drivers are more stable than Nvidia's.
https://www.notebookcheck.net/Sick-of-video-drivers-crashing-Independent-auditor-finds-AMD-s-drivers-are-more-stable-than-Nvidia-s.316564.0.html