Great Images! I had the first version of the Sigma 12-24, and with care to avoid flare, it was really useful. I did send it back to Sigma originally to adjust the centering which improved the evenness of sharpness across the right and left field. Then I added a Canon 14 II, which I also sent back to Canon to even out the field. Then Sigma came out with 12-24 II, which I bought to figure out which one would be best to keep.
I turned out the Sigma 12-24 II was a bit sharper overall, and controlled flare better. At the setting of 14mm, the Sigma beat my Canon 14 II, all at an optimum setting of f8-11. F 16 causes diffraction to degrade image quality in all these lenses.
So I sold the Sigma 12-24 version 1 and the Canon 14 II. All tests done on 5D II, RAW and Lightroom processing, esp. for color fringing control.
In the end, it's the photographer and his/her technique, angle selection and lighting that counts, and the client has to be happy.