The FX-6300 and a GTX 660/660 ti would be a perfect match. I have been using both AMD and Nvidia in the systems I have built over the years with never an issue with either one. A lot of problems folks have is they don't keep their systems clean of registry errors, junk files, and resource wasting crap. That's why I always recommend:
1) Uninstalling the previous driver before installing the new one. Also, run Driver sweeper from Safe Mode after removal of the old driver to remove any AMD, ATI, and Nvidia remnants left behind.
http://www.techspot.com/downloads/4266-driver-sweeper.html
2) Running CCleaner after the driver uninstall/reboot.
https://www.piriform.com/ccleaner Do the Clean and Registry portions both.
If I had to make a judgement call, I'd say Nvidia cards and drivers are even a bit more stable than AMD.