Japanese itself changed significantly from 1987 to 2017. The internet, globalization, and shifts in honorific usage (keigo) made the 1987 text feel stiff to younger readers. The 2017 revision softens archaic constructions and improves the flow of dialogue. For example, the use of kata (方) for "person" has been adjusted for natural speech patterns. A "better" PDF will highlight these changes in a preface or appendix.
If you own the physical Shinkaiyaku 2017 (published by the Japan Bible Society, ISBN: 978-4802082291), you can take it to a print shop (e.g., Kinko’s in Japan) to have the spine cut off and the pages scanned at 600dpi with OCR. This is expensive (¥5,000+) but produces a permanent, personal digital archive. shinkaiyaku 2017 pdf better
When users search for "Shinkaiyaku 2017 PDF better," they are usually encountering one of two problems: Japanese itself changed significantly from 1987 to 2017