Do You Prefer to Read Classic of Contemporary Mysteries? Why?
This is going to be a cop-out answer, but...both.
I teach a "Drama and the Novel" course, and my syllabus usually includes two classics, like Mousetrap, Hound of the Baskervilles, or The Glass Key, and works by two contemporary crime novelists--Sue Grafton, Walter Mosely, or (a favorite of my students) Qiu Xiaolong.
On the classic side, I can't get enough of Josephine Tey. Daughter of Time is one of the most original novels ever, and even her lesser works like To Love and Be Wise are entertaining and witty Her writing can be curmudgeonly, but is always sharp and betrays a deep perceptiveness and love for the truth. She doesn't suffer fools, and neither does her recurring protagonist, Inspector Grant.
On the contemporary side, I just finished Bull Mountain by Brian Panowich. There was tremendous buzz around the book heading into Bouchercon, and the convention's book rooms actually sold out. The book deserves its praise. A multi-generational crime saga and the Burroughs family, it reads like an episode of Justified co-written by Daniel Woodrell and Nick Cave. Really fun stuff.