Supporter :
Still waiting for a clear winner, for now nvidia and amd are still exchanging massive blows at each other.
AdaptiveSync will 'win' eventually since it is part of the DisplayPort specification and every scaler will eventually include it. A few years from now, it will be nearly impossible to get a display without AdaptiveSync support since it adds practically no cost.
Unless Nvidia manages to maintain its GPU performance and efficiency lead well enough to convince people to pick G-Sync which costs ~$150 extra over AdaptiveSync, Nvidia will eventually be forced to implement it either as a footnote in their tech specs or under a different marketing name from AMD's FreeSync.
I bet Nvidia already has some degree of AdaptiveSync support in Maxwell chips, just waiting for a firmware and driver update to enable it if they start hemorrhaging sales specifically due to much cheaper FreeSync monitors.