It's natural for long-established characters to change and evolve over time, so that there is no single "definitive" version. Is Batman a gun-toting loner, a friendly father figure, a deadpan square in a campy and psychedelic world, or a grim, borderline-paranoid avenger in the worst city on Earth? Is the Doctor a tetchy old grandfather or a feckless cosmic tramp or a debonair swashbucker or any of eight other personalities? Is Commander Shepard a man or a woman?
Arguing over the "real" version of a character is just arguing over personal preference. There is no "real" version, since they're all imaginary. Fictional worlds, characters, or continuities can be changed in ways reality can't (although history can certainly be distorted to change people's beliefs about reality). And the dominant version of a character can change over time as generational tastes and perspectives change. I think that by now, the dominant image of Nick Fury in popular culture has fundamentally changed, due to the sheer number and influence of the various works that have embraced that new image, and due to the potency of the new image itself. It's a change that resonates with our multicultural times, and as TemporalFlux
says, it's a change that works for the character.
I also agree with TF
that it seems weird now to see Fury portrayed with anything other than his Samuel L. Jackson-style look. The hybrid version of A:EMH, with old-style Fury's full head of graying hair, looks weird to me. It's not as striking and effective a look as the bald, goateed Fury. Maybe I react that way because that Fury reminds me of Captain Sisko on Deep Space Nine
, and thus that look more strongly evokes a powerful, badass authority figure for me.