Chandler, hands-down. Tight prose, irony, wit, and a great descriptive sense. He can also really tell a story, of course--you're with him even when the plot doesn't make sense.
I would have to say Ken Bruen...while I love the typical style of fiction writing, Bruen's writing is unique in that it often feels like he's stabbing at a pool of words and is only nabbing the very best to use- brief yet powerful.
Carole - have you ever tried the Ripley series by Patricia Highsmith - she also wrote the book Strangers on a Train, which the film was based on. If not, I think you would enjoy those - I feel that Highsmith really paved the way for Ruth Rendell in terms of psychological crime/thriller books.
Right now I'm dead-crazy about Giles Blunt. His latest stand-alone, "Breaking Lorca", made me cry out loud to the alarm of my kids, and this is something that isn't easy to do. His prior book "No Such Creature" was hysterical. And I loved every second of his Cardinal Series. His grasp of the human condition is profound.
Didn't mean to go on about it, but for currently-prolific writers in the genre, he gets my vote.
Blunt is excellent. This has been a great thread to read. It's good to see a number of my favorites on here. I sense that what makes a great stylist is someone who can make the book flow.
I'm just getting into Leonard and his dialogue is great. Makes you turn the pages. But sometimes I want a little more than dialogue.