Here's how it looks for me.
1. I use a 0-byte 'paperbook' file to filter my physical books.
2. I use a custom 'ratings' column in order to use a 10-point scale instead of the default 5-point one.
3. I use an integer #percentread and a
template that converts them into a reading status. But it's easier to just use a boolean like JSWolf suggested.
4. Knowing when a book was last read is useful sometimes.
5. Chapter, page, and wordcounts, though for obvious reason I skip wordcounts for paper books.
6. Book type: I have Fiction, Nonfiction, Fanfiction, Comics, Magazines & Periodicals, and Documentation & Manuals. This mostly is for sorting into virtual libraries.
7. Some Kobo-specific columns. This is for eBooks on my device.
8. Filedate and filename are also for eBooks -- I get them automatically with a plugin.
I also have a bunch of fanfic-specific columns and one specific to documentation/manuals, but I hid them for the screenshot.