I'd recommend getting the AF-S 35 mm f/1.8G 1st. (7 rounded aperture blades)
The 50 1.4 has a 1/3 - 1/2 stop or aperture advantage, better build quality, an AF motor and 2 more (9) aperture blades than the 50 1.8. (7 rounded aperture blades)
The build quality of the 50 1.8 is more than sufficient for normal use. If you figure to use a 50mm on a near daily basis, get the 50 1.4.
The 2 extra aperture blade will give slightly better bokeh. Were you to be shown images made at the same aperture of the exact same scene, it's doubtful most people could tell by looking at the images alone, which lens took which image.