Depends on how you want to group them. The ones that are ”worth it” in my books are the last of the three main families: basic models Coolscan IV and Coolscan V, more automated models Super Coolscan 4000 and Super Coolscan 5000, and finally the medium format models Super Coolscan 8000 and Super Coolscan 9000. Some of these are USB, some are Firewire.

— cabba, Reddit