watched all the Luthers, loved it. Knowingly did all the cop cliches really well. Was at its best when they had Alice as a Moriarty with a helpful twist.
Line of Duty is similar but better in a way. In Luther, when Luther is under suspicion of being dirty, everyone immediately assumes he is guilty and a similar thing happens with other wrongfully accused suspects. In Line of Duty there is always at least one frustrated town player who's not so convinced and wants to explore a bit. Or sometimes they just seem really town...