* Liber bonus: This is the most straightforward translation, literally meaning "good book." "Bonus" is a common and versatile adjective for "good."
* Liber optimus: This translates to "best book," implying it's superior to other books. "Optimus" is the superlative of "bonus."
* Liber excellens: This means "excellent book," suggesting high quality and merit.
* Liber egregius: This translates to "outstanding book" or "remarkable book," implying something exceptional.
The best choice depends on the context. For a general "good book," liber bonus is perfectly acceptable.