The two from your list that are at the top of mine are Michael Connelly and John Sandford. I have the same problem of running out of good authors in the genre. I have had to branch out from straight cops and PI's. I like the Bookman series by John Dunning. His hero is an ex-cop who is a rare book dealer. It sounds like a strange combination, but it works. Dunning has been a rare book dealer and there is some fascinating stuff in there for people who like books and murder. I also liked his book based around the radio industry in its prime, "Two O'Clock Eastern War Time". Dunning is also a world class expert on old time radio. Psychologist Jonathan Kellerman does pretty well with his psychologist/profiler hero, Alex Delaware. If you read Kellerman's nonfiction monograph, "Violent Spawn", about psychopaths you'd see how he can have a nice cynical edge for a shrink. Kellerman's friend Stephen White has a kind of similar protagonist who works in Boulder Colorado. This guy spends a lot more time worrying about patient confidentiality than Delaware ever does, but the plots and characters are interesting. I don't think that Stephen White knows a lot about firearms and explosives, but his crazy Colorado locales are appealing.
I've only read one book by Christopher Hyde, A Gathering of Saints, but it was a truly fine read. There is a serial killer operating during the London blitz who seems to have access to the Ultra decryptions. Hyde has great information of how things really were during the blitz in contrast to all the "stiff upper lip" stuff that was published in the American press during the war. Read this book.
I've only read one book by Giles Blunt, Forty Words for Sorrow, but it was also really good. This has a cop in the Great White North looking for a serial killer.
If you are willing to consider a woman author and a woman detective you should consider the author Kathy Reichs who is forensic anthropologist for the Office of the Chief Medical Examiner, State of North Carolina. Her protagonist, Tempe Brennan, is similarly employed in Quebec and gets involved in a lot of nasty cases. I don't like it when Tempe seems to get panicked in a feminine way, but the serious technical details and the plots make these pretty interesting. Reichs is one of the few woman mystery riders that I really enjoy.
For off the wall odd stuff you ought to look at the Mamur Zapt series by Michael Pearce. The hero is a Brittish civil servant who is the head of the Egyptian Secret Police around 1908. Due to some weird turns in the affairs of the Brittish and Ottoman empires, Brittain ends up effectively running Egypt around the turn of the last century. Officially they don't run the place, but in practice they do. A Britt ends up as the "Mamur Zapt" who is supposed to see that nothing with political overtones gets out of hand. The intrigue is great and the cultural clashes are hilarious. These are out of the mainstream, but very enjoyable.
