There have been plenty of detective shows on TV over the years, but I'm willing to argue that Monk is the best series of that genre. While the mysteries themselves are not always as dramatic as those on CSI or True Detective, the characters in Monk set it apart.
Mr. Monk was a brilliant detective in San Francisco until his wife Trudy was murdered. Her death causes Monk to have a breakdown and develop pretty serious OCD. The show surrounds him working with the police department as a private detective, while coping with his OCD and trying to catch his wife's murderer.
Tony Shalhoub develops the character of Monk so perfectly throughout the entire series. He is loveably neurotic, with a list of over 300 fears (including milk and ladybugs, obviously) that lead to plenty of awkward situations, but ultimately provide him with the sharp observational skills that make him San Francisco's best detective.
Monk himself is a source of a lot of humor on the show, as are the relationships he develops with his assistant and the two detectives at SFPD. The four are a perfect team, solving tough crimes all while helping Monk change his OCD from crippling to manageable. Over eight seasons you only get to know four or five characters, but you get to know them really well.
Monk is the perfect series for anyone who likes crime shows, but also really enjoys getting invested in the characters they watch. For a quick glimpse into the series, watch the intro, which highlights the characters, Monk's OCD and his detective work. Plus the song is really catchy.