Don't disagree with anything you've said there. I wouldn't deny his warrior spirit, Displayed clearly vs Evander, Stewart, Briggs, Moorer and others. But the OP was after who fought with real passion in the ring and while Young George could really put his all into a fight - he really had a fire in him when he fought Joe Roman - Old George took, as you say, a 'calculated approach', conserving stamina, as he had to. I don't doubt his natural instinct would have been to go balls to the wall like he had back in the day but he overrode that and kept calm. So I can't say he showed great passion in the ring. And I do also believe he was utterly dispassionate after the fight. His celebration when he beat Moorer was incredibly muted. Two months earlier, Oliver McCall showed how to celebrate with passion - he went batsh1t crazy, actually - when he beat Lennox. Compared to the airborne splits Oliver pulled, or Mike Weaver's gymnastics floorshow when he beat Carl Williams, George just gives off the indifferent air of someone who really could just take it or leave it. I think you're probably right that he had a great passion for boxing, not just in his returning but also in his continuing long after he was set up financially. It just wasn't the vibe you got from him.
I wouldn't consider the 1st 3 face first fighters. They were aggressive. But also very skilled at slipping, parrying, blocking , and riding punches...In fact, Frazier and Duran were two of the greatest fighters noted for their aggression, but extremely underrated for the defensive know how.
True, they are underrated defensive masters, esp. Duran, but Frazier and Briscoe often took terrible beatings in their careers, despite great defensive skills.
Id have to change my choice for the most passionate fighter by the definition of the criteria to Fighting Harada. Good chat indeed I hope to hear more from you.
When your older everything is twice as hard, so you have to fight smart and pace yourself. He had composure and a poker face.