Although I have read my share of mysteries over the years, my preference really is for crime fiction that does not feature the overworked "who done it" formula.
In my younger days I liked the James Bond novels, early Forsyth, early Ludlum, etc. That was more espionage stuff, but I think these days I would prefer more "noirish" works--James M. Cain and work in that vein. I also like Elmore Leonard, though I have not read much of his work.
I am looking for atmosphere and suspense--not so much mystery.