I just tried my 4th... Yes, 4th copy of the Sigma 35... I have written Sigma off at this point. I tried, but I just could not deal with the AF.
The first two I tried right when the lens came out... MA changed heavily indoors vs. outdoors... 0 MA near to far outdoors, +10 required indoors. Was a PITA.
Fast forward to last week, I tried another. Copy 1 seemed to work fine indoors vs. outdoors but was decentered... OK, just get another... I have had plenty of Canon lenses that I needed to exchange.
Got the replacement, indoors to outdoors is perfectly fine (thankfully). However, the AF is just way too darn unreliable. Some shots are so far OOF you wonder how the camera ever thought it was right. Yet the next photo be perfectly sharp, the next somewhat soft, sharp again, way out of focus the next, etc... Mostly near infinity focus it had these issues.
I just slapped my 35L back on and sent the Sigma back home for the last time... Until Sigma can have even better AF, the Canon options are for me.