My .02...
On a side note, Nikon did make the 58mm f1.2 Noct which is an extraordinary lens -- one has to wonder how much of that design went into this lens? Agree with the above that had this been a 58/1.2AF -- even if it added $1000 to teh price -- it would be more compelling for me.
What is the diameter of the rear element on the 50/1.2 AI-S and the Noct-Nikkor? I suspect that the contacts required for an auto-focus lens wouldn't fit between a rear element of that size and the mount. I guess this is why Nikon doesn't make f/1.2 F-mount lenses any longer.
There have been several mentions of the Zeiss ZF.2 50/2 Makro-Planar as a perfect 50, but I do not personally share that opinion. My first ZF lens was the 100/2 Makro-Planar, which I love, apart from the CA it has. Lovely rendering, gorgeous boke and fall-off.
Naturally, the 50MP was my second lens, but from the first shot I made with it, something was different. The gorgeous boke and rendering and fall-off I loved from the 100MP was gone, replaced by a kind of tense, strained boke, and the depth of field was very fat, aperture for aperture, and the fall-off was unattractive. Furthermore, wide open the extreme corners are somewhat muddy and dark, and the field curvature there is very strong. Focusing at 5-8m with trees around, I could see branches pop into focus way back in the corners.
Note that close up the 50MP has nicer boke and less problems over all, but then, I can't recall having seen any lens with lousy boke at macro range.
I do find that the 50MP is a nice portrait lens. The fat DoF helps reduce the fuzzy nose and ears problem without bringing the background into focus wholesale. For this reason, I still own it.
The ZF 50/1.4 Planar is an odd lens. The first time I tried one (borrowed from a friend), I couldn't get along with it at all. Everything I tried was soft with purple fringing. I rejected it outright, until I got another chance a while later, and my experience couldn't have been more different. It turns out that the first time I had inadvertently used it close up, wide open, in high-contrast situations, where is pretty much sucks.
Change just one of those parameters, and things look very different. It is more like some Leicas in that it has resolution enough, but with a veil over it, and not as high-contrast as many other Zeiss lenses. Stop it down a little and it rapidly gets contrastier and sharper, and by f/5.6 it is one of the sharpest lenses I have used, and matches the 50MP. I cannot confirm or deny Jack's suggestion that the corners aren't sharp even at f/8, because I rarely shoot subject matter which needs to be that sharp, that far out. It is good out there, but maybe not perfect.
Unlike the 50MP, the rendering is beautiful, from wide open, at almost all distances. Using the 50MP up close and the 50P from maybe 2m and out would make a good set, and that is more or less what I do.
Disclaimer: I use a D800, not the D800E. I didn't need the extra sharpness, and don't particularly find that it even looks natural, but more like digital artifacts. The slightly better moire control and lower price are also fine with me, but weren't the real reason. The D800 has quite a light AA filter, and pixel-for-pixel, it is sharper than my D3 was.
I have also used the Leica 50mm f/1.4 Summilux-R E60, and although it has a lovely look, I find it much too expensive for what you get, and I also found it very hard to focus, due to its gentle sharpness transition. The 50 Lux-M ASPH was one of my favorite lenses ever, so I say this with a heavy heart.
I find the Otus intellectually interesting, but it doesn't touch my heart, just my gear gland. The new Noct is another matter, and I am another close watcher. The lack of outright sharpness wide open doesn't bother me. I think we have been focusing much too much on sharpness in recent times, and look forward to seeing what great portraits and other photos can be made with this lens.
I have the Sigma 50/1.4, and it has gorgeous if neutral boke, but I find myself not using it. The lack-lustre and unreliable autofocus has something to do with it, as does the fact that it doesn't pick up much sharpness on being stopped down.
I am probably also going to pick up a nice 50/1.2 AI-S at some point. Yes, I am a 50mm (and 35mm) junkie.
N.B. I picked up a Sony A7 two days ago, and find that I can focus any of my 35 and 50mm f/1.4 lenses wide open, without using focus magnification. That EVF is wonderful, and I find it hard not to think that the writing is on the wall for my beloved optical viewfinders, unless something changes dramatically in how Nikon makes and optimises them.