IMO, he hit a purple patch between (IIRC) 1995 and maybe 2003. Before then things seemed a bit patchy, but for me
Strangers and
Watchers hinted at what was to come. I can't say I reckoned much to
Lightning myself - at least memory tells me that, while I got through it and it killed a few hours easily enough at the time, it didn't stay with me as a Great or Highly Enjoyable Read. The period where I thought he was at his best probably started with
Dark Rivers of the Heart (which seems both quaint and prescient now) and ended pretty much around the time of
The Taking. Pretty much anything in between is a good read, IMO, and
False Memory will always hold a bit of a special place because it was one of the two books that got me through a very sticky spell in early-through-late 2000 (the other book was by some other chap - King, I think his name was - and the book was summat to do with Hearts and Atlantis
).