Which 50 do you like on FX and why?

I've had both 1.4 and 1.8 versions, plus the Sigma.

Sigma 50mm 1.4 is my favorite, quite sharp at the center with the best bokeh. It's a HUGE lens, so I think some folks skip it.

Nikon 50mm 1.8G is my second favorite. In spite of some saying the 1.4G is sharper, I did not find this on D800 or D700 and I had more than one sample to try.

Now...if we're going to be seriously honest here, ALL of the 50mm lenses are excellent and you'd be hard pressed to see much difference between them when actually shooting. If YOU take a good photo ANY of these lenses will do a fine job.

Robert