This is probably an even harder question than my favourite OTP because, for example, I love Psycho-Pass and Gekkan Shoujo Nozaki-kun but for completely different reasons and then there’s also the nostalgia I have attached to shows like Prétear and Sailor Moon.
But ultimately, I would have to say that ERASED (Boku dake ga Inai Machi) takes the biscuit. The story is great, the cinematography is cool, the ending is 100% satisfying.
Unlike a lot of crime dramas, they actually bothered to give you (rather obvious in hindsight) hints to solve it yourself so, as a crime drama lover myself, when we found out who the culprit was I was kicking myself for not wanting to suspect them.
But seriously, if you like crime dramas, check it out because it won’t disappoint.