Which Nikon lense do you prefer and why?

Nikkor AF-S DX 35mm f/1.8G Lens

or

Nikon NIKKOR AF-S 50mm f/1.8 Lens

I don't use a Nikon, but if I did it would be the 50mm. (and I would probably go for the f/1.4G) since I have little to no use for a 35mm lens on my Canon (the 17-40mm does just fine), the same would hold true if it was a Nikon (or Pentax, or any other DSLR).

If I'm going to replace the 18-55VR or the 18-105VR, the 16-85VR (all these lenses are AF-S) has always been my favorite, sharper and much better built.

On a DX body, the 35mm due to the field of view. However, that's my preference.
What you need to do is tape your focal length to the appropriate focal length and shoot for awhile to determine which focal length best suits you.