PhysX is kinda cool I suppose but its not really that big a deal and only a handfull of games support it. And its really only something that I personally dont notice that much when actually gaming. During demos it stands out but when youre actually playing, youre probably not going to notice it.
So while its cool and all Im not sure Id buy a GPU based solely on that.
As for G-Sync, that could be very cool but itll depend on how many monitors adopt it. The only one I know of right now that has it is an Asus 24" The new Asus Swift ROG 27" monitor will have it but it keeps getting delayed but is "supposed" to be out July 14th AFAIK at around $800 USD. So while its gonna be pretty cool, its not going to be that readily available for a while at least and youre gonna have to pay a little extra for it so again, not sure its worth basing my GPU purchase on IMO.