Which would you choose and why?
I like the canon for the reliable AF, ability to go FF (I shoot film some), and the 45mm view on crop vs 48 on the sigma- I don't like the corner softness and CA.
I like the sigma for the F1.4, and edge in sharpness wide open, especially at the corners.- I don't like the focusing problems and lack of FF compatibility.
The zeiss should blow the others out of the water in sharpness and contrast. Its easy to mount adapt to canon (C/Y mount). I have an EF-S screen already so focusing isn't a problem.- I really don't like that diaphragm will be manual operation and stop down metering.