Always and forever, though, and far, far more important is: who is the detective—because, let’s face it, the victim only appears in one story, seeing as how she/he is the victim and sort of dead by definition.
But a good detective can appear in tons of stories. Sexton Blake, for example, who was called by some the ‘poor man’s Sherlock Holmes’ and, according to Wikipedia, ‘Sexton Blake adventures appeared in a wide variety of British and international publications (in many languages) from 1893 to 1978, running to over 4,000 stories by some 200 different authors.’
Four. Thousand. Stories. There are fifty-six Holmes short stories and four novels by Conan Doyle, and how many ‘additions’ to the canon since? One of my personal favorite series is the Mary Russell/Sherlock Holmes novels by Laurie K. King, but there are literally thousands more. And there are dozens of Nero Wolfe/Rex Stout novels, stories and novellas.
Now, what is the link in these? Why, the detective, naturally. I re-read all my favorite mysteries, not to find out who dunnit, but to spend time with the detectives.
So I had to have a detective that I’d enjoy spending time with, one who had a reason to be in a mill village in the first place, and one who had his own ‘Watson’, his own ‘Archie’; in other words, someone who is telling the story and standing in for the reader.