There were many types of ink-screen e-books, and which one was better depended on personal preferences and needs. The following are some common features of ink screen e-books for your reference: 1. TLV format: TLV format is one of the most common e-book format, which can easily store text content. 2. PDF-format: PDF-format is a powerful document format that supports more document types and format. It can also be paginated. 3. ePub format: The ePub format is a popular e-book format that is lighter than the PDF-format and supports more text content and multiple pages. If you want to store more text content and need a lighter e-book, the ePub format might be more suitable for you. If you want to support more document types and format and need to paginate, then the PDF-format might be more suitable for you. Of course, if you don't have high requirements for the appearance and weight of the ink screen e-book, then the txt-format ink screen e-book is also a good choice.