I do as well. I think its more clear in the "better" category. Spinks was the more versatile, adaptable, and multidimensional of the two. But even in "greater" Spinks has the deeper resume of wins, and the accomplishment of becoming the first light heavyweight champion to win the heavyweight crown. I think its Spinks for both.
Better is a toss-up but greater has to be Chavez. He's a living legend while Spinks is most famous for his loss to Tyson. Yes it's sad, but it's a fact. It's also not just about the "casuals". Every boxing fan knows Chavez, while Spinks is pretty much relegated to talk of where he belongs on a list of best 175 pound fighters.
There's an argument to be made that Michael Spinks may possibly be the gratist light heavyweight champion of are times Chavez is rated as either the gratist or second gratist Mexican fighter of are times (Zarate); somehow Mexican citizen Joey Napoles is never mentioned at the top
No, the casual angle means everything. Spinks is best known to CASUALS for the Tyson loss. You know what Duran is best known for among casuals? The No Mas. Does that change the fact that he's a top 5-10 atg to real boxing fans? I would be careful for calling Chavez greater because he's a "living legend." Tyson is arguably the most legendary fighter in the sport's history. Does that make him the GOAT? I'm talking in terms of quality of opposition, and accomplishments, Spinks should be ranked higher. He made history. Chavez never did.
Zarate isn't even the greatest Mexican bantamweight. That title rightfully goes to Olivares. I just feel Zarate would beat Ruben H2H. But he's not greater.
What i'm saying is "greatness" is not some cold scientific analysis. (in boxing or in any other sport for that matter) You could have just left it at "better" if that was the case. Greatness is longevity, popularity, skills, accomplishments and the impact on a sport all rolled together. Take out the "casuals" and you'll have no shortage of people who still would have Chavez ahead and they won't all be Mexican either.
I get what you're saying, but popularity should be the last metric used here. If we put too much weight into popularity, it opens up a dangerous can of worms, where suddenly Oscar can be argued "greater" than Monzon.
Chavez's 87-0 record was a historic accomplishment though so he did make history - whether you think it counts as much (given the somewhat manufactured nature of that early DQ loss that was changed to a win) is another matter.