I’m going to read a Dean Koontz book. If I like it I’ll read more. You tell me which one to read first.
Don’t bother asking what I like in order to make a suggestion, just tell me. I’d tell you to base your suggestion on what you know about me from my history on the board but I don’t feel like reading a coloring book.
Watchers might be his best book, and will give you a good idea as to his style and the kind of things he writes. It’s about two escaped government genetic engineering experiments.
The one with the telepathic dog.
That’s Watchers. The dog is one of the two genetically engineered experiments that escaped from the government lab.
Watchers is good. The best advice I can give you is, don’t read too many. They start seeming all pretty much the same real fast. This has inspired me to make a new thread, because for a moment I thought, “Is Koontz the Thomas KinKade of horror novelists?”
But reast assured Koontz isn’t anywhere near that bad.
Lightning, Watchers, or Strangers. The rest are varying degrees of dreck.
Read “Fear Nothing.” I found it in a back alley last week, and I’m curious if it’s any good. 
Lightning. My month gave me a grocery sack full of his paperbacks and that’s the only one of them that I remember at all.
That one where it starts off with really creepy, spooky supernatural stuff going on, which really freaks out the main character who was up until then leading a normal life. But then it all turns out to be a government conspiracy.
I thinking there’s a Strong Woman™ in there somewhere too.
It’s been a while since I read it, but I liked Strange Highways. It’s a collection of stories, but the title story is a full novel.
Watchers is one of his best and nothing at all like the movie. It is certainly the best of the telepathic dog books. There was another book I liked better, but it’s been many years and they all run together after you’ve read a few. Watchers is a pretty good start–representative, yet more distinctive than a lot of the others.
I liked Fear Nothing okay, enough to read the sequel, Seize the Night. They are also about a super-smart genetically-altered dog, though. If you’re going to read one of those, go with Watchers.
I would not recommend Tick Tock to anyone, ever. It is distinctive, I guess, but not really representative. I hated it so much I stopped reading Koontz, so I have no idea about anything he’s done in the past ten years. This post may not apply to his more recent work, but I suspect that the best of his work was earlier in his career.
No one’s ever going to accuse Koontz of being a literary master. He won’t get anything close to the defenders that King has. He’s clearly found a formula that works for him, and he’s managed to get rich from it. I can’t fault him for that. There’s some talent buried in there, though, that shines through in Watchers, some of the stories in Strange Highways, and a few others. Beyond that, it probably doesn’t much matter which one you read. You either like the formula, or you don’t. But don’t read Tick Tock.
Dean Koontz novels are easy reads. The pages turn quickly and before you know it, you’re done. He’s a technically proficient but pedestrian writer. His earlier books are better than his later ones, probably because his editors were able to curb some of his more annoying habits. I wouldn’t recommend you read anything by him, but if you’re going to, then I guess I too would recommend the one about the dog. He does love dogs and it shows.
Lightning is his best, but I also enjoyed The Bad Place, Dragon Tears, and Cold Fire.
Fear Nothing and Seize the Night are quite good if you don’t want anything deep and meaningful. Creepy horror/SF with a lovable dog (required for all Koontz books). There is a third part of this series coming out sometime in the future.
Read The Taking. The last person I advised to didn’t regret it.
Any of these, and I would add Phantoms to that list.
I’ll read Koontz for an easy, fairly entertaining read. The exception is The Bad Place, which really got under my skin for some reason. I love that book, and I’ve reread it probably a couple of dozen times, which most Koontz doesn’t stand up to, IMO. So, that’s my recommendation.
Clockwork, I consider myself DK’s biggest fan. I have all of his books, have read them all at least three times, and have a few autographed copies. Not that that makes my opinion worth any more…but if anyone knows DK’s books, it’s me.
That said, heh, I’ll have to pretty much echo what’s already been said here. I love Strangers, Lightning, and Watchers. Most of his books are good, though. If you want some suggestions beyond what everyone has said in here (which is mostly the same three), I’d go with One Door Away From Heaven, By the Light of the Moon, The Face, and–my favorite DK book of all of them–From the Corner of His Eye.
I would NOT suggest Midnight, The Sight, Funhouse, or The Taking…while I think DK hasn’t written a bad book (yet), I’d say these four got about as close as you could come to a bad book.
Depends on your mood…not what you like, what “flavor” of book you want.
Watchers, Strangers or Lightning.
Strangers has an Alfred Hitchcock feel: something’s going on, and our heroes are caught in the middle of a series of webs of lies and murder (Think “North by Northwest”)
Watchers has a more"family" feel, lotsa heartwarming stuff, punctuated by occasional horror. Vaguely “Spider-Man 1” flavor.
Lightning feels like a James Cameron (early Cameron before he became preachy and annoying) flick. Think “Terminator”. Hell, I’ve always pictured the main male character as being Arnold.
Any of the three are a really good read. Most of Koontz’s other stuff is schlock.
Oh yeah? 
Anti-Men
The Crimson Witch
Hanging On
and about a half-dozen others from that period.
And (God have mercy on us all), his “Deanna Dwyer” books:
Children of the Storm (which I’ve tried to read)
The Doctor’s Office (which I’ve tried to read)
and the other three Dwyer books (which I’ve never actually seen) *
Justify THOSE, mister!
*For those not in the know, in the late '60s, early '70s, Koontz wrote 5(?) Romance novels under the pen-name Deanna Dwyer. To say that the writing is tragically bad doesn’t begin to cover the badness. He also ground out a cubic fuckton of schlock (of varying degrees of badness) under a bunch of pseudonyms. It wasn’t until about 1977 or so (When did Night Chills come out?) that he really found his voice, IMO.
I’d disagree.
His middle books, say 1980-2000m are better than his earlier or later ones.