Often 35mm output is fine, at other times 4x5 film is ideal. Excellent color fidelity. These two shouldn't be grouped together as greyscale shares most of the issues that are addressed when speaking of color. Greyscale does, however play into creating high quality output from line art, where greyscale allows for lines to be anti-aliased for a smoother look, at the expense of much larger images. Scanning Negatives and Transparencies Balance resolution, cost and color handling.
Drums are the top of the film scanning world.
In recent years only the Leaf 45 challenged drums. A new crop of challengers is emerging, including new, commercial flatbed scanners. That's not say that decent scans can't be made. It is simple. Couldn't they be making you money, instead of fooling around trying to fix low quality scans.