The-Digital-Picture has posted their extensive review of the popular Sigma 14mm f/1.8 DG HSM Art series lens. The praise for this lens continues with this review, it may be a niche product, but it looks like it's currently the best 14mm option for your full frame DSLR currently available.
From The-Digital Picture:
Easy to say is that this is the best 14mm f/1.8 DSLR lens ever produced, as there has never been another. Not hard to argue is that the Sigma 14mm f/1.8 Art Lens has the best 14mm image quality available to date. This lens delivers impressively sharp images, ranking very high in the entire field of lenses (not just among its ultra-wide peers). The design of this lens is aesthetically pleasing and the build quality similarly-good. The price will set you back a noticeable amount and the AF system may not leave you impressed, but the other aspects of this lens will make it a top choice for fulfilling the critical ultra-wide angle needs in many serious kits. Prepare to say “Wow!” when reviewing your images. Read the full review
I think it's time we get our hands on one of these unique lenses from Sigma.