Perry Mason!

Mason is one of my favorites too, although all the "Well, this is the one case you can't win, Perry!" gets a little tedious after about a dozen episodes! I've always greatly appreciated clever whodunit plotting (the "puzzle plot"), even when I do guess whodunit, and Perry Mason has surprisingly clever plots, with good suspects, clues, and alibis. I was watching one the other day--I think it was "The Case of the Weary Watchdog," starring Keye Luke of all people--and I was really surprised with the writers' ingenuity. In particular, there's a rather brilliant alibi. Perhaps I simply grew used to years of Murder, She Wrote and its ilk, which tend (with a few exceptions) to present just about no clues to the viewer and then give no ingenuity in the solution (though Columbo, despite its "inverted" format, always had clever plots).

The few detective shows nowadays that play fair? Actually, Death in Paradise is the only one I can think of right now!