Time to set aside the notion that AMD is better at DirectX 12. The two available benchmarks are long-standing AMD titles, one with its roots as an AMD tech demo and the other straight out of the AMD Gaming Evolved system. Very predictably, they show AMD doing better than Nvidia. Also predictably, they promote the one and only aspect of DirectX 12 where AMD has an advantage. These titles completely ignore those aspects of DirectX 12 where Nvidia holds the advantage, which include feature levels for which AMD cards are completely incapable. At this point, with only two AMD demos, the calls for AMDs superiority strongly echo those we heard when Mantle was released.
For the future, the advantage will be with whichever architecture scores the most wins in terms of game development relationships. In today's competitive landscape, it is a guarantee that any upcoming Nvidia sponsored titles will lean more heavily on raster processes and not so much on async compute. It is also a guarantee that the majority of games to be released in 2016 will favor Nvidia architecture, the architecture that 80% of gamers have in their rigs. This is already a reality to this point of the year.
Now the only caveat, and what I mean by "in this competitive landscape" is that there is also a very high likelihood that Nvidia will incorporate async compute capabilities into Pascal, and at a high level at that. At that point, then it's safe to assume that Nvidia-favoring game developers would follow suit and exploit those capabilities. Bottom line, Nvidia is best positioned to have games developed that feature the capabilities of its architecture, simply due to its dominant 80% discreet GPU market share.