The old 35mm f/2 D on a D700
I have had this lens for 3 years now. Bought it new.
Small, light, fast to focus, sharp enough wide open (for normal use and portraits), low distortion. Only drawback is the way it renders out of focus highlights - the bokeh is a bit busy.
Also great for indoor party shots.
But be cautious if price is too low. I have not seen used examples of this lens for cheap.