There are personal basic preferences that one develops over trial and error. Some people have excellent results with a particular product or model, others have different results.

Color registration is very important. Some scanners reproduce flourescent colors very well ... other scanners do a very poor job in that regard.

If you are going to use your scanner primarily for scanning chips and not flat objects like documents, photos, etc., you will want a scanner that scans 3-D items such as chips without casting too much background grays. I personally prefer a white background to a gray background.

If one wants a black background behind your chip images, all you have to do is scan with the cover open.