I disagree about The Rockford Files being the same show with little in the way about plot changes. I don't understand how you arrived at that conclusion.
To me, the most obvious difference between Rockford and Columbo was that Rockford was a down home, blue collar, working class, regular guy who lived in a dirty looking trailer on the beach, and most of the time was involved in cases that also involved more blue collar, street type people. Columbo tended to work cases that involved more well-heeled, upper class and wealthy people.
I used to watch Murdock Mysteries back in the early 2,000's when it was still only shown on a local public broadcasting station. I watched it for a couple of seasons then got kinda bored with it.
If you like detective shows, check out some of the Brit shows.
I used to love this one called "New Tricks" about three retired Scotland Yard detectives who were recruited to come back and work unsolved cases. Their boss was a younger woman who had to deal with their various personality quirks. Good show with a humorous edge to it as well.
Another one you might like is called "Dalziel and Pascoe".
https://upload.wikimedia.org/wikipedia/en/2/24/Dalzielandpascoe.jpg
I think my favorite of them all was a series called "Inspector George Gently" that took place starting out in the early 1960's and progressed through the entire decade as the series progressed.
https://i.ebayimg.com/images/g/HMQAAOSw7rReQgIM/s-l640.jpg
