Canon 50mm 1.4 OR Sigma 50mm 1.4

Same experience here with the sigma: after calibration by Sigma tolerable accuracy at close distances. Anything 3 metres and beyond forget it. Not even consistent so micro adjust won't help.

Actual optical quality is, as others have said,better at wide apertures than Canon; about the same at f2.8 and worse thereafter.

Having said that the Canon is tolerably sharp in a narrow central area even wide open; a bit low in u-contrast at wide open but nothing that some 'clarity' in lightroom can't fix. And it's wonderful at smaller apertures.

Gotta say there is room in the Canon ecosystem for a modern sharp fast focussing fast but not ultrafast 50mm lens. Either a 50 1.4 II or a 50 2.0 macro