From Jhreg to Dzur all are amazing, my favorite is Phoenix however, because it is written first person, as a “how to” of assasination in the Dragearean Empire.
The whole series has a dark humor that is flooring. They are written is such a way as you can pick up any one in the series (knowing nothing from the others) and be perfectly fine, plus the writer throws in little hints of things in other books. Sometimes things not even written about yet.