(the informal poll results)
(Laura Holt, Columbo were mentioned)
Of course, there is no right answer. Everyone has a different opinion.
Personally, I vote for Sam Spade, because he could take a kick to the head and still function. A tough guy in a trench coat.
And he disarmed ‘the gunsel’ of TWO 1911s, which put him in solid with his boss!
I am surprised no one mentioned Mike Hammer?