The design on the Sigma is newer and has bigger glass, so the color rendition is better and it creates better bokeh. It is also sharper at f/1.4 than Canon, but when it is stopped down, the Canon becomes sharper. I was lucky enough to buy mine for the same price as the Canon though. There isn't enough difference between the 2 to justify the higher price on the Sigma. So if you're looking at getting the Canon, it will be just fine.