This is a 100% detail of a Sony a7 (top) to Nikon DF (bottom) low light comparison shot at ISO 12800 on Steve Huff's site... no sharpening, out-of-camera Jpegs.
I have taken the liberty of trying to normalize the images. I down-sampled the 24MP Sony a7 image to match the 16MP DF proportions and also applied Topaz deNoise 'moderate' noise reduction.
On the other hand, I sharpened the Nikon DF image(USM 120,0.4,2) as well as a -30 brightness in Photoshop. The Sony noise reduction procedure is the largest loss of information.
The Sony's Jpeg engine creates ugly noise patterns during the in-camera demosaicing process and both cameras produce mush colored areas....understandable at this high ISO. The a7 has better DR for whatever reason.
I am unable to explain the softer Nikon image unless "zero noise reduction' is significantly not zero. Some have speculated its the Nikon portrait lens but I don't buy that.
There is too much loss of detail unless there were minor focusing issues.
The bottom line is that I believe these are both creditable attempts at this ISO with pluses and minuses to both images. I'll pick the higher res Sony as the most usable. A similar Raw comparison would be nice.