Q) Which is better for scanning – negative or positive film?
A) Generally speaking, color negative (C-41) film is a dream to scan relative to transparency (E6) and black and white films. Color negative not only captures a huge dynamic range but compresses it to a very small dynamic range that’s easy for scanners to extract. Color negative film allow allows the photographer to print in either color or black and white. Images can be scanned in color mode and in front of the lens filtration (yellow filter, red filter, etc) can be simulated during the process of converting the image to a grayscale mode. Fuji has concentrated recent efforts on tweaking their new color negative films to be even more optimal for scanning. Some B&W neg films (like TMAX 100) can be problematic because they can exceed the dynamic range of the scanner so you have to loose some of either the highlights or shadows.
Now, there are always exceptions. Some scanner software applications aren’t great at handling color from color negatives. Some drum scanner applications, for example, just don’t know what to do with the orange mask and it would take a super skilled operator to overcome the software limitations to get good scan out of it. Most drum scanning applications were designed to scan transparency films so you might hear an operator say E6 is best for scanning (at least on *his* scanner system). Finally, some people might prefer to shoot their favorite B&W neg film for the sake of the unique grain structure.
Imacon/Hasselblad and Nikon scanners are great for color negative scanning and with those scanners you’ll probably want to shoot color neg, especially Fuji’s latest flavors.