FWIW, I have owned the Nikkor 70-200mm and currently use the Sony equivalent. They are 2 of the best lenses I have used. Of course that is by far my most used focal length range.
The Sony 70-200/2.8 seems to have some peculiarities which make it ideal for portraits and events, but less than optimal as an all-purpose lens which also has to shoot landscapes, buildings, etc.
Essentially, it's much sharper at portrait distance, and other nearer distances, than it is at infinity.
This is probably why some tests, shooting at portrait distance, say it's the sharpest 70-200 out there, but others, shooting at infinity, find it to be poorer than its Canon and Nikon counterparts.
The 90/2.8 macro exhibits this behaviour to an even greater extent, but, as a dedicated macro lens and labelled as such, can be excused for it - it's meant to be optimised for close subjects, not shooting at infinity.
The 70-200/2.8 is probably designed that way too, to an extent, to satisfy its event/wedding/portrait photographer base, but this leaves it less than ideal as an all-round short-to-medium telephoto lens. In the focal lengths that it overlaps, the 100-400/4.5-5.6 has no such predilection for shorter focus distances, and, when shooting more distant subjects at the same focal length and aperture, seems sharper.
Also, like a lot of other Sony lenses, it also seems to have significant copy-to-copy variation. I've seen some that were as sharp as the Nikon, as well as others so soft I thought they were from a cheap telephoto bundled with an entry-level body and a kit lens.