Spoiler: when the subject is Muhammad Ali, the documentary wins.

“Biopic vs Documentary”; or “Impersonation and Camera Techniques vs Archival Footage and Editing”; or “What’s the point of doing the former when the latter is way more interesting?”

Muhammad Ali was a remarkable human being – larger than life, charismatic entertainer, civil rights activist, champion. Stories about him demand to be told (most vocally by himself). The “Rumble in the Jungle” between an older comeback-Ali and the younger, terrifyingly peak-condition challenger George Foreman is the perfect story to showcase this remarkable character.

Will Smith is a charismatic entertainer. Michael Mann makes riveting films. Both clearly gave their all to make “Ali” – from Smith’s charm augmented by his physical transformation, to Mann’s pioneering camera work and fight scene staging – and, were its real-life subject less amazing, “Ali” could be regarded on its own merits as a real cinematic achievement.

But here’s the thing: the real-life footage exists. Ali was not only well-photographed, but he was also well-written – and by himself, no less – an improv king. And live improvisation, when done well, will always have an element of drama and excitement than no recreation will ever capture or recreate, by definition: the high-wire stakes, the feeling that this is happening, it may all go wrong at any moment, and therefore every moment it goes right is a miracle to witness. “When We Were Kings” comes as close as any film can to recreating this feeling – director Leon Gast’s footage selections and editing choices help distill the excitement of the moment in history, and the force of nature that was Ali.

I was prompted to ask similar questions after watching “Get On Up“, which stars Chadwick Boseman as James Brown. Aside from “Ray” and “Malcolm X“, there are few biopics I rate as being worth watching, or don’t question why they were made at all. (And, like “Ray”, the film’s real-life subject had at least some involvement):

For all his own charisma and talent, Will Smith impersonating Muhammad Ali only ever comes across as Will Smith impersonating Muhammad Ali. And for all his experimental and usually engaging film-making techniques, Michael Mann literally putting us in the ring, in the line of fire of the boxers’ gloves, still doesn’t put us in the ring in quite the way that the collage of television replays and commentary from people who were covering the event at the time does. This is criticism not of Mann or Smith, and not so much of “Ali” (which I do think drags a bit at times), but of the biopic as a form. And this is, by extension, a celebration of the documentary, and of such remarkable people whose stories demand to be told.