Sigma 16mm f/1.4 DC DN Contemporary has been very well reviewed by the few that have managed to get their hands on it. Even DPReview holds it above the other options available at this time. It’s previously been said that this lens could have been called an ART lens and that doesn’t seem to be an exaggeration.
Sigma 16mm f/1.4 DC DN: B&H Photo / Amazon / Adorama