I really like the 28-70mm f2.8 tokina. I used it for 10 years with photojournalism. I found it reliable well made and sharp. Tokina also has good warrenties. I had on major issue and they sent me a new lens quickly. I do not recommend this lens for Canons because they really need the built in motors for AF, Nikon does not. Also you may look at this lens 18-70mm f/3.5-4.5G ED-IF AF-S DX Zoom Nikkor. Tokina does not take full advantage of Nikon DX tech.
Ps. I shot this image with the tokina at f2.8