@Stefanos Love all the Nikon Standard primes, have both the 55m f1.2 and 50mm f1.2 both seem equally sharp wide open, the 50mm a smidge sharper but my shoddy eyes can't quite be sure. But sharpness isn't always what's called for in my work:
I prefer the Nikon 50mm f1.4 over the Nikon 50mm f1.8. The 1.8 is sharper, but I like bokeh at every given aperture with the 50mm 1.4 than I do with the 1.8. I had a 1.4, sold it to get a 1.8 because I heard and saw with my own eyes the increased sharpnest of the 1.8. However, when I looked at my video with the 1.8 and the kowa 2X anamorphic lenses for bell and howell and the 1.4 with the same anamorphic lenses attached, I realized that I liked the image from the 50mm 1.4 much better.
Here are two examples: (They look better in HD on Vimeo)