The Nikon 50mm f/1.4G does everything right, so is our winner. It's a good weight and feels well balanced on the camera. Build quality is reassuringly rugged, and the ring-type ultrasonic autofocus system works a treat on any Nikon body.
Plus, considering it costs less than the bulkier and heavier Sigma equivalent, it's a bargain.
Modernity isn't everything, of course, and proving that classics still have a lot to offer the digital photographer, Nikon's 50mm f/1.8D delivers spectacularly sharp images with bags of contrast and is an absolute steal at £100/$125.
However, it won't autofocus on bodies such as the D3100 and D5100, which lack a screw drive for camera-based autofocus actuation. Therefore, the newer Nikon 50mm f/1.8G is the next best thing if you're on a tight budget.
The Sigma 28mm works best as a wide-angle lens on full-frame cameras, but is a bit on the large and heavy side for a 'standard' prime on APS-C format bodies. The Sigma 30mm is a better option for DX shooters but isn't without its flaws - the most noticeable is a lack of sharpness at the edges and corners of the frame.
The Sigma 50mm f/2.8 and Tokina 35mm f/2.8 macro lenses offer full life-size magnification at their closest focus distances but, ultimately, the smaller maximum aperture makes them a bit of a compromise for general shooting.