Haven't really been keeping up these days but I think a while back it was the case that a lot of developers seemed to make their games best played on Nvidia, taking advantage of a lot of their technologies. That was when I gave up on AMD even though it was a terrible practice to support. In fairness, I have never had a problem with poor performance since with a game that isn't solved immediately through a driver fix or something. I believe AMD have much improved drivers, but I'm not sure if games are still targeting Nvidia more often than not.
Is FreeSync equivalent to GSync? My understanding is it wasn't quite as good, but I might be wrong on that.
But as a company to support, Nvidia seem incredibly shitty in terms of their practices. Proprietary technologies and monopolistic practices is a bad look when there is only one other competitor. But I've heard people say they have a better developer outreach problem, hence the reason behind the support they get.