See my Sigma DG HSM Art wishlist.
This medium-far range series evaluates lens performance from f/1.4 through f/11 paying special attention to focus shift in combination with sharpness across the frame and near to far but also discussing secondary color and bokeh and distortion as significant wins.
Include images up to full camera resolution.
The Sigma 40mm f/1.4 DG HSM Art is surely one of the finest 35mm optics ever produced and yet its focus shift is troubling in practice in terms of getting the very best results. Still, at about $1399, the value in terms of cost vs performance is perhaps unprecedented, and it blows away the Nikon NIKKOR Z 50mm f/1.8 S on the Nikon Z7, if a lens adapter and the weight/size are acceptable.