My oounion might not be the most popular, but I think Canon still has the edge when it comes to the final outcome. I just want to see 35L II and the updated hi res 50L. AF is still not 100% reliable with Sigma, but where Sigma is loosing is the bokeh. Bokeh that Sigma produces is not so pleasing, very nervous. Bokeh is a lot, a lot more important for poryraits that corner sharpness. Bokeh and AF are the 2 key things for portraits. Sharpness and resolution is what is more critical for landscapes. In this case, I think Sigma is not really Art...it is more S as sharpness. Do not be surprised that in real life you will enjoy portraits produced with 50 L more. Photographing a chart nas nothing in common with real life application.