I'm sure it comes as no surprise, but my vote for best film scanner for B&W is the Leafscan.
The reason being it uses a single neutral density filter for B&W scans, instead of using all three (or even one or more) of the color channels to "derive" a B&W scan. I know that CCD scans that use all three color channels are somewhat fuzzier, simply because of the smear and bloom most apparent in the red channel, then the blue channel. The green certainly is the best channel if you have to use color for B&W scans, IMO.
