I'm a mood reader. Sometimes I want a long trial, sometimes a quick fix. For this series, that doesn't work. The continuity of character is the through-line. Your mood might suit a later book's tone, but you'll sacrifice understanding. Tough luck. Read in order.
Wait, are the audiobooks narrated by the same person? Because if they are, that could influence the order too. Hearing the same voice might make bouncing around less jarring.
The practical answer: If you walk into a bookstore or library, they'll likely be filed in this order: 'The Lincoln Lawyer', 'The Brass Verdict', 'The Reversal', 'The Fifth Witness', 'The Gods of Guilt', 'The Law of Innocence', 'Resurrection Walk'. That's it. Don't overthink it. Grab the first one and see if you like his voice. If you do, just keep going to the right on the shelf.
Look, the Netflix series might bring new fans, and they'll ask this. The answer is simple: read the books in the order they were published. The show might adapt out of order, but the books have a steadfast internal chronology. Start with 'The Lincoln Lawyer'. It's the origin story. Everything else follows from there. Trying to start with season two's source material ('The Fifth Witness') would be confusing because Haller's life situation is different. Book order equals story order. Don't complicate a good thing.
Okay, but has anyone else noticed how the definition of 'Lincoln Lawyer' evolves? At first it's a literal description of his office. Later, it's almost a brand, and then a legacy. That thematic thread is best appreciated chronologically.