So many suggestions possible with that prompt.

I might suggest the Vlad Taltos series, starting with Jhereg, by Steven Brust. Reaslistic characters, snappy dialog, interesting premise of human's status in the society, and a pretty far-out series of villains. It comes down to more or less a first person assassin- / intrigue-based plot with cleverly set-up who-dunnit elements here and there, and an overarching storyline, and a good sense of the universe.

Some good suggestions in this thread. If you want even more options - I have been tapping into this Slashdot thread for a decade now, and it's still giving me winners - which might not work for you, mind (e.g ."Little, Big" by Crowley, it led me to "To Reign in Hell" also by Brust, "Jack of Shadows" by Zelazny,)