I definitely feel the Law of Diminishing Returns applies to Bond reference books for me. Every time one is announced, I’m all for it and every time I get it in my hands I think, “I’ve gotta stop buying these things.”
I’ll always feel the fondest for the first ones I found: Steven Jay Rubin’s “The James Bond Films” and soon after that Benson’s “Bedside Companion.” Of the two, Benson’s is the more valuable as a scholarly work, but mostly for the “novels” section as there’s too much opinion involved in the discussion of the films (and I don’t usually agree with those opinions, so there’s that). Rubin’s book is comparatively superficial but it was so exciting at the time to have a whole book devoted to Bond I didn’t even notice for a while that not one photo was an officially endorsed one from Eon.
Soon after, I found a second-hand copy of the first version of John Brosnan’s book and devoured it eagerly even though much of it was spent summarizing plots (no longer necessary in the age of home video). I searched for years to find the 2nd edition that would update the chronology through Moonraker (even though I was pretty sure he would dump on Roger, which he did).
Since then, the books have gotten longer and more lavishly illustrated, often on higher quality paper, but for me also progressively less interesting. Part of it is doubtless having already heard so many of the stories and part of it is that as the series moves on, less and less of each book interests me. When “Legacy” came out, I thumbed through it, realized fully one fourth of the book dealt with films I didn’t much care for, and put it back on the shelf (I eventually bought it on the cheap, second-hand). I did get Taschen’s “Archives” book but the same effect set in: I breezed through the chapters on the Connery to Dalton eras, slogged through Brosnan over the course of a few months and finally came to a dead stop halfway through QoS, with the rest of the book as yet unfinished to this day.
I think I’m fondest of the books that focus on one little corner of Bond’s world, like Roger’s LALD “Diary,” Helfenstein’s labor of love OHMSS tome, John Glen’s “For My Eyes Only” and so on. Plus I have an odd fondness for “Adrian Turner on Goldfinger,” a quaint little “A to Z” formatted book that I bought in a Canadian bookstore just to have something to read on a plane and ended up really enjoying.
Another oddball favorite, though not exactly a “reference” per se, is DK’s “Secret World of 007” featuring creatively drawn cross-sections of various lairs and vehicles from the films in the spirit of Stephen Biesty’s books about ships and buildings. It’s probably meant for kids, but I love it.
I should also say that it’s always a trade-off where Eon’s involved. I find officially approved books are usually better illustrated and benefit from access to their vaults, but it’s usually the “non sanctioned” ones that are the most fascinating and revealing, by a long shot.
And it’s not a book per se, but a few years ago Cinema Retro did a wonderful and very fat (maybe 128 pages?) square-bound magazine tribute to Doctor No that I really enjoyed. I wish they’d do similar ones for the other series, but as I don’t think that one has completely sold through to this day, it seems unlikely.