High quality lens with autofocus incorrect

I wanted to make this lens to my new "always on it" on my Canon EOS 70D. There I also really liked the picture quality, feel and handling, but the autofocus worked significantly worse than Canon's EF-S lenses with STM-drive. If I had only activated, for example the central cross-type sensor, the Sigma lens has partially can not focus. A replacement lens had the same mistake.
So from my side no buy recommendation. Perhaps the AF works in combination with another DSLR but better.