Nikon AF Nikkor 50mm f/1.4D
Despite its age, this old favourite still has much to offer for the modern photographer. It's an ideal partner to full-frame DSLRs, but also works well on DX as a short portrait lens. It offers the usual advantages of a prime, i.e. a bright maximum aperture for low light and shallow depth-of-field work, coupled with excellent image quality when stopped down; in both regards it offers users capabilities which simply aren't available from zooms.
Everyday photography on full-frame and APS-C, where its excellent sharpness deliver great results at optimal apertures
Wide-open use on full-frame DSLRs, where heavy vignetting and poor corner sharpness can cause issues (unless you like the effect) and lack of built-in AF motor limits usefulness on entry-level Nikon DSLRs.