Adam Maas , Jul 25, 2005; 11:42 a.m.
The 35-70 is better built, optically much better and faster. AF should be about the same speed on an F100, courtesy of the powerful AF motor and the 35-70's wider aperture. On the D70, the 24-85 will be faster in decent light, but the 35-70 will perform better in low light (The Multi-CAM900 AF module has poor low-light performance, which the 35-70's larger aperture would alleviate).
The 35-70 will perform better wide-open, and should have somewhat better bokeh. I'd get it unless you need the extra reach of the 24-85.