Comments about Off Brand Tokina Atx 28-70 2.6/2.8 Pro F/nikn Afd:
I owned both the Nikon 28mm-70mm 2.8 and the Tokina 28mm-70mm 2.6-2.8 at the same time. Both are big and fast. They are both very excellent optics. The slight nod goes to the Nikon, but I kept the Tokina. Why? I took the extra 1K and bought a Tokina 20mm-35 and a Tokina 80mm-400mm.
This trio works very well with my Nikon set-up (F5, D1X, and SB80). I still own a bit of Nikon glass, but The Tokina AT-X lenses give me a better value for the dollar.