Star Trek discussion

Impact can be taken in a variety of ways - your choice :-) To me, Sarek hit me hard. Wow - I really was blown away with this one. Both was an excellent piece on Vulcan emotion, but also open my mind to Sarek as a character, his relationship with Spock, and generally was a fantastic read. Sarek

A couple that come to m ind:

The James Blish adaptions: these helped get me hooked on TOS

Final Frontier by Diane Carey: Not the movie, but a story of Kirk's dad, as first officer on the Enterprise's test run.
Love this book. Still have a copy on my shelf.

Case of the colonist's corpse: Kirk and co. are bit players, as this is about the lawyer, Sam Conley: love the idea that side characters could get their own stories.

"Most impactful" is a little different from "the book that I enjoyed the most".

I have to second Travis's vote: the ST books that had the most impact on me were definitely James Blish's novelizations. Those books got me started on reading ST and almost half a century later, I'm still reading ST books.

Over the years since I started with Mr. Blish's offerings, I have found a few other books that I enjoyed more, but I never would have found those other books had it not been for James Blish.