f/1.4 was less sharp wide open than either the f/1.2 or f/1.8 II, and the f/1.4 was “too hazy and dreamy” and too soft to be usable wide open unless you want a dreamy look akin to smearing vaseline on your lens
at f/2.0, the bokeh of the f/1.2 lens is a touch nicer than that of the other 2 lenses at that aperture
the three lenses produce identical results from f/4 although color and contrast rendition was best with the f/1.2 lens and poorest with the f/1.8 lens
“the 1.8’s and the 1.4’s build quality leave a lot to be desired”
“the Canon 50mm f/1.4 is just that much more disappointing because although it is 3-4x more expensive than the 50mm f/1.8, its build quality and overall image performance doesn’t come to justifying the additional cost”
“the Canon 50mm f/1.4, even though it has a maximum aperture of f/1.4, its overly soft image quality at wide open nullifies that extra half stop advantage. And if you stop down to f/1.8 or f/2.0, then there really not enough aesthetic difference in appearance to the 50mm f/1.8. On top of that, its build quality is barely any better than the 50mm f/1.8”