Sounds like the Sigma 35mm is sharper but perhaps there is too much rosey enthusiasm about this lens among some. I am glad to have Canon play defense... competition is always good for the customers but let me share my subjective view of the Sigma pictures I've seen so far.
When I first saw the Sigma head shot of the girl here on the forum somewhere (someone please link it if you remember), my thoughts were: beautiful subject, sharp lens, very nice OOF but the bokeh is not very pleasing. Granted, one can't look at football-shaped off focus lights always to judge this.. they all tend to look the same...one needs to look at real world backgrounds ...and the quality of the bokeh is not always measurable...it is subjective. I simply did not like the Sigma rendition. There was also something about the color...microcontrast...I dunno... Sigma was clearly a sharp lens but it did not speak to me.
Now, in all fairness, had the Canon 35L been used on the same model, same night lighting, would it be any better? I don't know as there was no head-to-head comparison. So I hope for Sigma's sake that Canon 35L would also have produced the same picture.
But what is more significant is that lensrentals gallery in their Sigma review/blog also has those rather flat looking pictures with color rendition that just doesn't grab me. And Roger from lensrental goes on to say bokeh is in fact subpar with this lens. Another review cited in this thread earlier also states the same thing about the Sigma bokeh.
So sharpness is not everything. There is such a thing as "Je ne sais quoi" about the images that lenses generate and I think 35L has it in spades. It hasn't seen much use with me for some time...but perhaps it is time I paid an old friend some much deserved attention.
