I don't have the Sigma Art 40mm f/1.4, but if you can tolerate its 1200g heft
, based on the quantitative measurements and tests I've seen and previously reported upon, you'll be rewarded with class leading centre and edge sharpness, contrast, ultralow chromatic aberration, and great corner performance (low coma and astigmatism) in the medium wide-angle range.
See lenstip.com for data and comparisons with other lenses.
Best
JA