Brian K. Vaughn. Everything he touches is gold. Gold, Jerry!
I’d have to add J.K. Rowling to the list, too. I can’t imagine not reading the next thing the writes.
Stephen King definately used to be on the list. Not so much anymore. I still like him, but I can’t buy one of his books without at least getting a feel for it first.
I call this my “Refrigerator” list. If one of the authors on my list were to put their name on a refrigerator, I’d do everything I could to get it. At this point, I’m willing to trust them, no matter how outside my normal tastes their story might sound.
Lindsay Davis
Michael F. Flynn (BTW, is there a collection available with the original version of Eifelheim?)
Jane Lindskold
Eric Flint
David Weber
Lois McMaster Bujold
Tim Powers
Harry Turtledove used to be on my list, but he’s given me some letdowns in the past 8 years or so.
Harry Turtledove’s work is now only good for lining the inside of furnaces. The first invasion series he wrote was great, the second one was utter cack.
Anyway, my choices:
Tom Holt (even if some of his books are extremely variable in quality)
Garth Nix
Susanna Clarke (Of Jonathan Strange and Mr Norrell fame)
Iain M Banks
Danny Wallace
Jasper Fforde
Oh, and Neal Stephenson, Neal Stephenson, Neal Stephenson and Neal Stephenson.
I want to add Terry Pratchett to this list but I’ve read the blurb for his latest book and unless I read some compelling reviews I’m going to give it a pass.
Jack Vance; not that there’s likely to be much except a brief autobiography…
Neal Stephenson
Kim Stanley Robinson
M. John Harrison
Jeffrey Barlough; impatiently awaiting v5 of his Western Lights series…
Jonathan Carroll
Margaret Elphinstone is the most recent to make the list; I doubt I’ll read her earliest books, but the last 3 or 4 have been excellent…
Michael Swanwick hovers on the edge - I’ve read them all but swithered for weeks before buying a couple of them…
I’ll definitely go along with Steven King, James Lee Burke, David Gemmell and Lee Child, but I’ll also add that, I’ve never read a bad John Sandford book.
No chance of any more David Gemmell books, I’m afraid… he died almost two years ago from complications following heart surgery. 
So that’s why I’ve not seen any new titles recently! He really is/was a marvelous storyteller!
Me three on Carl Hiaasen and Martha Grimes (except for her standalone books set in the American Southwest – those have just been irritating). Also: Ruth Rendell, Lisa Scottoline, Tess Gerritsen, Preston & Child (love me some Agent Pendergast). Have been reading Baldacci at the request of my husband’s uncle, who loves him. Some I like, some I don’t.
I believe I own nearly everything published by, and (for the living authors) would buy anything new written by:
Joe Haldeman
Octavia Butler
Robert Heinlein
Connie Willis
Sharon Kay Penman
Diana Gabaldon
Patrick O’Brian
James Herriot
I’d say Bujold, but I haven’t tried her Sharing Knife series yet.
I’m still working my way through Steven Saylor, George MacDonald Fraser, Bernard Cornwell, Georgette Heyer, George R. R. Martin and Michael Flynn, but they’re all candidates for eventual all-inclusive collections.
The first two books are awesome, easily up to the standard of Curse of Chalion, and Paladin of Souls. The third is merely a decent LMB book. Which only puts in the top 1-2% of fiction I’ve ever read. 
More seriously, I recommend all three books if you’ve enjoyed her other fantasies.
He no longer makes this list for me, but he does still write good stuff. Avoid the series stuff that he churns out to pay for his 3 daughters in college. Get the one offs he writes, like In The Presence of Mine Enemies, Ruled Britannia, or Opening Atlantis. Much higher quality.
And I would have to add Lois McMaster Bujold to my list. She wasn’t on it for some reason back at the start of this thread.
Michael Chabon (I’ve read everything of his, and he’s let me down only a couple of times)
**Cormac McCarthy ** (I’ve read nearly everything of his, and he has never let me down)
Leif Enger (with two books in the last six years, he’s pretty easy to keep track of)
Neil Gaiman, Stephen King, Carl Hiassan, John LeCarre, Frank Herbert, and of course: Asimov, Clarke, and Heinlein. I’m hope to someday have read everything written by those three, but, uh, Asimov alone wrote several hundred, so it’s taking a while.
Of any of the above, Gaiman is by far my favorite: I’ve read everything he’s written and every single one has led to one of those marathon ‘it’s really late and I really should just go to sleep but I can’t possibly put this book down’ sessions.
Umberto Eco
Iain (M and not M ) Banks, his last two peeved me a little, but I know I will unfailing pick up his next one.
Russel Banks, love his books, even if they are a tad depressing
Neil Gaiman
Terry Pratchett
Gerald Durrell (this ones dates from my childhood)
J D Salinger
Orhan Pamuk
Chuck Pahlaniuk
Isaac Asimov
Frank Herbert
Truman Capote
J K Rowling
Phillip Pullman
Johnathan Safran Foer
Some of these are about how I feel when I read their books, not about how good their writing is.
Keeping in mind that the OP is five years old:
Ed McBain - dead now
Spider Robinson - boring now
Donald Westlake/Richard Stark - formulaic now
Connie Willis - nothing now
Terry Pratchett - Alzheimers now
I need some new writers.
Pratchett doesn’t have Alzheimers yet, just the early signs that he will eventually. It’s not stopping him from writing.
I used to pick books more along those lines. I used to pick up anything by Stephen King, Douglas Adams, Dean Koontz, Michael Chrichton, and Isaac Asimov. But after a certain point I stopped. With the exception of Douglas Adams, who if still alive I would still rush out to buy anything he wrote. I’ve read all of Dan Brown’s stuff and will likely pick up his next one.
I’m not sure books that are in a series really count as in the spirit of this OP. While I would definitely pick up another Harry Potter book, for example, I wouldn’t necessarily rush out to buy the next thing Rowling did that wasn’t Harry Potter.
I’ve been having trouble for the last ten year finding authors I consistently love. I had hopes for Greg Egan because I really loved the first book of his I read, but haven’t been able to really get into the next one I borrowed from the library. Might have just been my mood though. I’ll give it another chance. Part of the problem is probably the internet. I spend a lot of my free time reading stuff on the internet, so I’m not as motivated to read novels recreationally since between the net and tivo I’m essentially over entertained now.
Neal Stephenson (who has a new one coming out in September)
J.A. Jance (new book on Tuesday)
Michael Connelly (new book in October)
John Irving
Tim Dorsey
Carl Hiaasen
Tim Powers
Jack Vance
Giles Blunt
Donald Westlake
Robert Crais
Preston & Childs
Daniel Silva
Michael Connelly
T. Jefferson Parker
James Swain
And I am amazed that no one mentioned
Tony Hillerman