70-200mm 2.8: Sigma or Tamron or neither?

From the reviews I've read, the Tamron has very good image quality throughout the range, with slightly reduced sharpness wide open. The big problem seems to be inconsistent accuracy of focus.

The Sigma seems to have the opposite problem, with accurate and fast focussing, but somewhat compromised image quality at the 200mm and with macro use.

I'm hoping for some guidance as to which one to get and how to work around the weak points. At this point, I'm leaning towards the Tamron, so I do have one question: is the focussing issue on all samples or just a few that happened to get professionally tested?