On the general topic, no holds barred. A few starter ideas:
Has the macho factor changed over time? If so, in what direction?
Who is/was the epitome of macho?
Who is the most macho actor working today?
Which movie had (or has) the most macho cast?
Which TV series had (or has) the most macho cast?
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Add more questions and/or subtopics as you see fit.
Most of the macho actors in Hollywood these days seem to be British or Australian; no more all-American two-fisted fightin’ he-men.
As a wimpy white chic, my instinct is to counter with “Vin Diesel” and “The Rock”. They’re both American, aren’t they?
Danny Trejo is the most macho actor today. Him and Charles Bronson in an arm wrestling match for the title.
Sam Elliot.
John Wayne?
Brian Blessed.
Hard to make a solid argument against The Duke, but I offer Robert Mitchum and Burt Lancaster as possibilities. And then there’s Steve McQueen in the next generation.
He’s not macho, he’s a wild yeti.
(He’s also a vegetarian, which I think disqualifies him, despite all his other feats of manliness.)
He’s punched the Dalai Lama and a polar bear in the fucking face. I think we can forgive him one flaw.
Macho in as much as a guy who can answer the question “is someone with 18 strength and 1d10 hit points per level a macho or a weak person?” truthfully and without hesitating. But that’s cooler now than it was 20 years ago.
The factual answer to #4 is the Expendables series. I mean that’s kind of the point of it!
Have you looked at Stallone’s eyebrows lately? Man looks like an 80 year old drag queen.
Mark Wahlberg, who has so much swagger he played a guy named “Swagger,” recently took a break from playing soldiers and cops to shirtlessly uppercut folks as The Fighter, after which he took roles from ‘Navy SEAL’ to ‘private eye of the fistfight-and-car-chase type’ to ‘steroid-fueled bodybuilder who turns to a life of crime’.
Oh, and he’s apparently the go-to guy for a Six Million Dollar Man movie.
They both are, and they’re both good examples of the evolution of the movie “tough guy.” Both tend to come across, both on and to a lesser extent off screen, as smarter and more nuanced than 80s-style action heroes. Arnold and Sly are both demonstrably smart dudes in real life, but their film roles tended to be pretty consistently meathead. And guys like Van Damme and Seagal seem positively cartoonish in hindsight.
Anthony Quinn.
This thread is now done.
I see a whole lot of Anglos listed - surely the answer of “Most macho” would be more along the lines of Antonio Banderas or Danny Trejo 
Hence Spy Kids is the most macho movie 
(OK, Desperado, then)
ETA: Quinn gets a pass. Points off for the namechange.
Danny Trejo gets my vote for “most macho”, regardless, BTW.
Nah, Banderas is actually quite the puss… add my vote to Trejo.
Lee Marvin’s gotta make the list somewhere.