Favourites, in no particular order:
Carl Hiaasen - Stormy Weather
Joe Gores - 32 Cadillacs
Kinky Friedman - Elvis, Jesus And Coca-Cola
James Lee Burke - Purple Cane Road
Robert B. Parker - Double Play
Lawrence Block - A Long Line Of Dead Men
Richard Price - Freedomland
Ian Rankin - The Falls
Least favourites, again in no real order:
Dennis Lehane
P. D. James
Andrew Vachss
James Ellroy
Ruth Rendell
P.D. James is actually my favorite crime writer. 
Funny, I’d put Ellroy at the top of my list, and Hiaasen near the bottom.
PD James is my favourite too. Even though she says “orientate” a lot.
Favorite: Raymond Chandler.
Least: Joan Hess. Entertaining and funny, but not mysteries at all.
Jim Thompson is not only my favorite crime/noir writer, but perhaps one of my favorite authors overall. I don’t think I’ve ever read any novel that has such a visceral, kick in the guts ending as The Grifters. I loaned it to Miss Moneypenny, whose isn’t a hardcore reader, and she read the thing in one sitting, and with the same response. 'Course, some of his work is utter crap, but at his best (The Grifters, Pop. 1280, After Dark, My Sweet) are outstanding.
Ditto for Patricia Highsmith. Although her Ripley novels are most well known, I think Cry Of The Owl is probably the best thing she wrote. Again, some of her work could be dismissed without loss (a fact to which she openly admitted while alive) but at her best, she was the best.
James M. Cain and Raymond Chandler are also good. I used to like Gregory MacDonald before he milked the Fletch series into the ground. I’m sorry he sold the rights to a studio who used it as a Chevy Chase project, but then again, so is he, apparently. I’ve never read Parker’s work, but people speak so highly of it I probably should.
I like James Ellroy’s short fiction but find his novels (or at least, the later ones) to be bloated, and his “shotgun” prose to be overly stylistic and unimaginative. He clearly does extenisve research, but often the historical facts and secondary characters seem to exist soley for the purpose of letting the reader know exactly how much research he did. I haven’t read White Jazz or L.A. Confidential, of which I’ve heard people describe as being his best work, so I’m not going to cut him off entirely, but he’s not number one on the list.
I never got the appeal of Vacchs. A lot of people like him, I guess; I find his work cliched and tedious. He claims to write in short bursts between court functions and whatnot, and I can believe it, as he seems to meander around from one subplot to another until coming to a completely irrelevent denouement. I give him master props for his work as a legal advocate for abused children, but I think is writing sucks. Sorry, Andy.
For the most part, it’s a genre I just don’t get into all that much. Crime/mystery for it’s own sake just isn’t that interesting, and a failure of much of the genre writing is that it is either about the crime and not the characters, or the characters are so…deliberately idiosyncratic, so unlike anyone you’d ever meet in real life, that it just comes off as a characture. Roy Dillon or Tom Ripley just seem like normal guys, albeit (in Ripley’s case) with a rather distorted, sociopathic view of the world.
Stranger
Favourite:
Dorothy L. Sayers
Leslie Charteris
Raymond Chandler
Dick Francis
Reginald Hill
Ellis Peters
Peter Corris
Kerry Greenwood
Ian Rankin
Least favourite:
I have an absolutely irrational loathing of Agatha Christie’s writing.
Ruth Rendell
But basically you can sit me down with any old mystery novel and I’ll be happy. My grandmother read the genre almost exclusively when I was a kid so they’re my comfortable fall-back.
I’ll second Jim Thompson. Amazing.
I’m a huge fan of James Ellroy and Carl Hiaasen, plus of course Raymond Chandler, Dashiell Hammett, and oh yes, Mickey Spillane. I keep wanting to get into Donald Westlake/Richard Stark, who I have been told I would love. Is he/are they any good? And what is Kinky Friedman like?
Westlake/Stark is very good but kind of a chameleon in style; he just doesn’t seem to have an identifiable style. He puts together solid stories, though, with well-developed characters, and has worked in so many different forms (novels, short fiction, short-shorts, TV, feature screenplays) that he’s demonstrated a mastery of not only crime novel genre but of adapting a story to any appropriate medium. (I believe he was nominated for an Oscar for adapting The Grifters to film.)
I like his short fiction best, and he’s all over any Alfred Hitchcock’s anthology, so it’s not hard to find. Give him a try; he’s well worth the read.
I’m surprised no one has yet mentioned Robert Bloch. He’s another solid crime author. There’s one story–I forget the name–about an embezzler who stashes some money under a sappling before turning himself in, and first plans and then relies on the money hidden under the tree to support his life after prison. The twist–that the money is missing–is obvious, but the story, about how his actions and decisions revolve around the hidden cash, is outstanding.
Stranger
Favorite: too many to write down.
Least fave: James Patterson. How in hell he gets money for writing I’ll never know. He is a really really bad writer.
I love Andrew Vachss, because I love over the top stuff a lot, and his is wicked over the top. Plus he’s a pretty good writer most of the time. And I think Max the Silent is just fucking cool.
Damn, I forgot Thompson: The Getaway is utterly terrifying, especially the almost magical-realist ending. Almost no relation to either of the movie adaptations, which weren’t bad but weren’t Thompson.
I can’t stand Ellroy’s prose style: it’s like he wants to be an Important Writer {tm}, and figures that being impenetrable is how you do it {not crime fiction, but yes, Neal Stephenson, I’m looking at you too}. And Andrew Vachss would probably be happier writing Batman graphic novels - you know, the dark, “serious” ones.
What is Kinky Friedman like, Big Bad Voodoo Lou? Completely nuts, and almost impossible to summarise. The real KF is a Jewish Texan C&W singer {no, really: his band is called The Texas Jewboys}, who carries this persona into his books, where he’s an amateur NY detective surrounded by and abetted/hindered by a supporting cast of loony friends. Murder, philosophy, drunkeness, drug-taking and killer one-liners ensue. They’re like no other books, and some people hate them, but do check them out - if you like them, you get addicted.
Fav: Gladys Mitchell I’ve never read a book of her’s that I didn’t like. Dorothy L. Sayers is good. Agatha Christie wrote 54 years worth of crap, but in the first few years she wrote a few really good stories (only 3 that I’ve found but they are there). Other than that the detection club tended to be pretty good.
As for least favs: I can’t think of any! I tend to find someone I like and stick with them (and it will take me a long time to find and read all the out of print G.M.s).
Absolute favorite: Ed McBain. He’s the grand old master of the genre.
I like Kinky & Vachss too.
The absolute worst, how the hell did she get a contract and do a series when she cannot write to save her soul is Sue Grafton. I’m sure there’s a spot in hell waiting for her.
Specifically what do you dislike about Sue Grafton?
Well I love Ruth Rendell/Barbara Vine. I wish that she would put away her London street atlas, though. Portions of her books read like Morington Crescent. No Night is Too Long and The Chimney Sweeper’s Boy are just about perfect, IMO.
Like:
Ruth Rendell
Tony Hillerman - these books are virtually all the same, but I enjoy them anyway.
Rex Stout
Alexander McCall Smith
CJ Box
PD James, with a couple of exceptions. I disliked The Murder Room and A Certain Justice.
Charles Todd - nice First World War crime books.
Douglas Preston and Lincoln Child - calling these “crime novels” is a stretch, but I included them because Agent Pendergast is my favorite detective, ever.
Dislike:
** Patricia Cornwell** - she has a few good characters, but horrible plots and unsatisfying resolutions. She needs a better editor.
James Patterson
I’ll admit, I only tried to read one of her books, and I found it just totally unreadable. It’s rare that I don’t finish a book, but her writing has no flow or style to it.
Doesn’t anyone but me like Ed McBain? He has been published since 1956, and his later works are as good as, if not better than, his earlier ones. And he started a series of alphabet titles long before Grafton did. Notably missing is “E,” as McBain has written "EXIT’ to be published after he dies.
Two current authors that haven’t been mentioned yet:
The good: John Connolly’s series of Charlie Parker (not the musician) novels is very good. He reminds me a bit of Faulkner, a bit of Thomas Harris, and somewhat more of Stephen King, though that may be because of his Maine setting. It’s also possibly because his series is about 95% mystery/thriller and 5%, well, fantasy, I guess. Start with his first book, Every Dead Thing, because his series really builds on itself. I mean, you could start later, but why? (Don’t bother with Bad Men, though, a mostly self-contained novel, unless you really love Connolly’s other stuff.)
The bad: James Swain. His Tony Valentine novels start out hamfisted and cliched and riddled with massive factual errors, and end up (as of the second-most-recent, the last I’ll read), actively offensive, using a 9/11-style conspiracy as a backdrop for a hamfisted and cliched “thriller.” Awful stuff.
I should probably give her another try. I just found her a bit dry and heavygoing. Of course I was probably 12 when I was knicking Granny’s library books to read 
Robert Van Gulik’s Judge Dee Mysteries, set in the Tang Dynasty era.