I quite enjoyed "Murder in the Eleventh House", by Mitchell Scott Lewis. It features a private detective that uses astrology to solve crimes. I don't know anything about astrology, but found this private detective approach new and interesting. I am reading the second book now...
Right now I like authors Peter Turnbull and Charles Finch. My goal was to read the 100 best mysteries (as seen on the internet). I loved "Chinaman's Chance" by Ross Thomas; Wilkie's "Moonstone" not so much. Elmore Leonard's "Get Shorty" made a better movie than a book---maybe because I like John Travolta.
Professional investigator who is not a part of a government agency.
Not constrained by rules like in the police procedural.
Private Eye is usually an outsider, intelligent and often physical
Can be cozy or hard-boiled