I wanna give it to Jamie Madrox or Kate Bishop, but I concede that Ben Urich is probably better.
A few come to mind, although some have been written off as spies and cloak and dagger types...
Nick Fury
The Prowler
Dakota North
Wolverine
Black Panther
The recently deceased Nighthawk
1 Thanos
2 Dr Doom
3 Adam Warlock
"You address omnipotence. Tread carefully."
I'd say a spy is a Detective. So Nick Fury would be the best out of essentially everyone in the Marvel universe at being a Detective. At a street level the question becomes different, but 'overall Detective' Nick Fury. Street level Jamie Madrox and I'd say those would be the two you'd go for.
I don't think Moon Knight gets the credit for how great he is. Nick Fury is top dog, but MK ain't no slouch.
"We live in a world of cowards. We live in a world full of small minds who are afraid. We are ruled by those who refuse to risk anything of their own. Who guard their over bloated paucities of power with money. With false reasoning. With measured hesitance. With prideful, recalcitrant inaction. With hateful invective. With weapons. F@#K these selfish fools and their prevailing world order." Tony Stark
I still alone I would have to say Black Panther, Daredevil and Jessica Jones. If we are talking about occupation solely then Jessica Jones Goes to the top of that list with honorable mention of Moon Knight.
To be fair, how would they do such a thing without looking like a Batman knock-off.
I suppose Ben Urich's basically a male Lois Lane - an investigative reporter who doesn't have superpowers, but uses detective skills to help the heroes anyway. Ironically, of course, he's most recently been seen with Spider-Woman, who should be no slouch in the investigation department herself being an ex-PI.
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