I reckoned that the 35mm would get more use. I have owned the Canon 35mm f/1.4 L in the past and this new lens appears to be far superior. It is very sharp wide open (as the shot below demonstrates) and renders out of focus areas beautifully.
In the shot below the focus point is on the eye. This is a fairly heavy crop. Viewing the original at 100% shows the eye to be silly-sharp! The Canon's 35mm f/1.4 is a great lens, but not ideal wide open unlike the Sigma. (Bob L - just order one!)
Canon EOS 5D Mark II, f/1.4 @ 35 mm, 1/200, ISO 400, Flash
Here's a picture of my colleague, Bryan, taken whilst on a business trip last week.
I wanted to capture lights in the background, but at a realistic brightness for the time of night. I dialled in some negative exposure compensation and used a wide aperture (which also helped to blur the background).
I liked the 'honest' nature of this portrait - no false smile or contrived expression.
Canon EOS-1Ds Mark III, f/1.2 @ 50 mm, 1/160, ISO 200, Flash