A99 tested on DXO - score: 89

Well you got to look at the whole package. The a99 out performs the D800. My D800 focuses as bad as my old E5 in live view, plus the a99 has a articulating screen, steady shot, focus peaking, focus range, EVF, ect. I had rather have those features and sacrifice a couple of DXO marks. IMO the a99 just has better technology behind it. It's all in what you want so if you insist on having the very best IQ buy Nikon. If you need more feature get the Sony.