And the winner is: EOS 5D Mark III . Mike Kobal made a quick comparison between the EOS 5d Mark III, the Nikon D800 and the Sony Nex-7. While I recommend you have a look at Mike’s post, I would like to quote from the article:
The clear winner for me is the Canon 5D mark III. Despite the overall softness right out of the camera (fixable in post to a certain degree), there are no aliasing and moire problems, records at a very descent variable bit-rate of 91megabits/sec in All-I mode and if that’s not enough, the 5D3 is also king after dark.
Let me also quote something concerning the D800:
When shooting stills, moiré and anti aliasing concerns across discussion forums are overblown topics. Of course it can occur and could be problematic. Especially when shooting fabrics, roof tiles, metal grids [...]
Nevertheless, EOS 5D Mark III is champion, next is the D800, and then comes the Nex-7. But: we are talking about moiré artefacts here, only about that.