Sigma's Art series of f/1.4 prime lenses has delivered consistently strong performance, and its latest entry, the 20mm F1.4 DG HSM Art ($899), is no exception. It manages to capture sharp, ultra-wide images, a heck of a lot of light, and focus close so you have the option of blurring the background...
Sharp from edge to edge; Minimal distortion; Short minimum focus distance; Available for multiple systems
Heavy; Dim corners and edges; No support for filters