It is all anecdotal as they say but when I got my first new F100, I got the Nikkor 28-105 and the lens was disappointingly crap. I sold it on Craig's list and bought a new 2.8 D 28-105 Tamron which was way better. Unfortunately also way bigger. I can't say that the Tamron is any better in build quality but it is amazingly sharp. Just on sharpness alone I would say it is on par or better than all my older Nikkor prime lenses.

I was preparing yesterday to take the 35-70 out for an environmental portrait of a couple and looking through it thinking about my subject to camera distance I noticed distortion. Or it sure looked like the straight lines on the edges were curving unless I was absolutely square to them. I decided to use the 85 instead. I am going to do some side by side tests and get some "anecdotal" info.
Thanks for all the replies