You need to ask yourself the following questions?
what are you using your scanner to scan?
What kind of scanner do you have?
who manufactures it?
What industry are you using this scanner for?
Next you need to check what kind of machine is commonly used in your industry
Then you need to check the specifications sheet of your scanner and that scanner
what you are looking to compare is ppi thats resolution like a monitor… higher better sharper
depth… more depth more range of colors
density range… how well it picks up subtle changes shadow details and brightness details
and typically if you are talking about serious scanning… and I mean serious scanning you are talking about a fuji machine and they aren’t cheap.