Nvidia. Within two weeks, their shitty drivers broke my system twice. If I didn't already know about that beforehand, I would've probably quit linux for good after that experience.
Out of curiosity, did you download the nvidia drivers with the distro's package manager or did you go to nvidia's website and do there installer thing? When I had an nvidia card I had plenty of problems over the years but I specifically remember that using the installer from nvidia's site caused all kinds of hell to break loose haha