Point deduction, there are also from me the Canon because of the missing lens hood and the lock switch. Clear advantage for the Sigma in point value as this is equipped with HSM. The opinions which the two lenses is now really better go obviously quite apart. I have a Sigma 18-125 OS HSM can not really test at my camera, so can only guess and refer to the reports of others.
After a few days I can say that the autofocus when Canon is quickly and accurately. The IS works great and the processing is in my opinion, for this price range also neat. The missing lock bothers me much less than feared initially, so I'm really glad that I chose for this lens as always top. The vignetting and barrel Verzeichung I can live with personally, as these can be easily with the Canon software (RAW) correct. In addition, one can not expect miracles from a lens with this focal length range and at this price, of course.
Addendum: Meanwhile, I use the lens to the EOS 550D. The peripheral light correction on the 550D works great and so I have, thanks to the good interaction between the lens and camera much more fun taking pictures! This situation is certainly not for quality fanatics who go regularly to figure Troubleshooting 200 magnification, but my expectations on camera and always plan are thus more than satisfied!
Hab now some individual pictures which I made with the lens.