Looking at a gamebook in pure game terms, as a contest between you and the writer, the book is simply a succession of game turns in which you have to choose one of three options. This is not a very complex game: even in noughts and crosses you get an average of 4½ choices per turn. The sad fact is that if a gamebook writer plays fair and gives you the chance to make an intelligent decision each time, then the game will be much too easy to solve. Instead they rely on dirty tricks: withholding information from you, giving seemingly sensible choices that lead you into inescapable danger, and killing you off as often as possible. That way the game takes longer, and the player gets more value out of it.
Pete Tamlyn, Crash 31, August 1986
For me this encapsulates the difference between Lone Wolf and Fighting Fantasy.
In it's day, Lone Wolf appeared to blow the doors clean off FF with it's believable world and branching structure that relied upon intelligent decision-making rather than luck/brute force/whim of Livingstone and a refusal to get drawn into "got to Boss encounter - only two of three required geegaws" territory. It's also how I managed to complete some of the early LW books (sans dice admittedly) on their first run through and then had no real desire to return to them.
It's clear to me now that, despite the criticisms of the FF format on gamebooks.org, the FF books have dated better than LW because they adopted the latter approach to gamebook design. A decent FF game is a great puzzlebox that requires multiple passes to completion and even then still has the "AAA" game to go after - the promised solution that minimizes the dice rolling and allows Mr. SKILL 7 STAMINA 14 LUCK 7 to get through.
Your correspondent here has the memory of a goldfish so gets a lot of replay value out of FF books that he hasn't touched for a decade or so. I don't really get much replay value out of LW books in the same way that I don't get much replay value out of RPG scenarios I've played in. It's odd, but back when I discovered LW I would never have believed that I would come around to thinking that this new approach to gamebooks, almost a real RPG campaign and everything, actually didn't have the legs of the approach that it appeared to be making obselete.
I still pick up FF books off eBay, I've only bought one LW book in the past 17/18 years or so and that was a second-hand Caverns of Kalte last week in order to fill an annoying gap in the run of the first 12 on my bookcase.
(The exception that proves the rule is of course Castle Death which has all the hallmarks of Joe Dever trying to write an FF book. It's one of my favourites and notably one of the LW fanbases least favourites).