If I may, I thoroughly agree with the Preston/Child Pendergast series. Read 'em all and loved 'em all. For real hard hitting crime/noir/atmosphere I don't think you can do better than James Lee Burke's David Robiceaux novels. I'd also like to suggest a fantasy series by Steven Erikson called The Malazan Book of the Fallen. Very dark, lots of world building, and you have to pay attention to everything that's going on. I've been reading The Expanse lately and enjoying those books as well.