JBR I know some have already been mentioned ... but I'll go ahead and list mine anyway.
My pick for enjoyment ....

Plus my non enjoyment pick ....
Detective series with a touch of comedy:
A Touch of Frost
The Last Detective
Heartbeat
Great characters and enjoyable:
Poirot
Grantchester
Foyle's War
Waking the Dead
Mild, wet, and boring = dull as dishwater:
Midsomer Murders - lousy acting by both Nettles and Dudgeon. Those two blokes must be the most boring men/detectives on the planet. The dog has more personality.
Miss Marple - doesn't grip me although I like the actresses who've played Miss Marple
Vera
Too repetative, although I liked her character, I find it irrating.
Dalziel and Pascoe
Chalk and cheese characters - Dalziel's very blunt and rude - (non-woke) with Pascoe being the very opposite.
'Meaty', 'Cut and Thrust' type plus 'Non-Woke'...Cream of the crops for me:
Rebus (Ken Stott brilliant as Rebus)
Endeavour/Morse/Lewis
The Sweeney
Plus Life on Mars.... totally different - great characters ie Sam Tyler and Gene Hunt portraying it like usually was in those days (apart from the sci-fi bit). Didn't enjoy the sequel Ashes to Ashes as much though.