Personally, I would go with two things:
1) It is impossible to determine who the greatest ever is; The caliber of competition changed a lot during the eras and through the weight categories, what should really exist is like a top 20 of the best ever without a ranking from last to first, this is way too subjective and I seriously do not believe we can hold such "roster".
2) Jones JR belong to the greatest ever; spending something like 10 years without losing a round, that's something indeed, he did damage his legacy toward the end, sure, but then again, how many great ones including ALi did the same thing? Not a big deal if you ask me.
He should considered in the greatest of all times, I would even dare to say that he might have had the fastest hands ever seen in the business during his prime but like all the other greats, he should not be considered THE greatest, matter of fact, I would dare to put at least one name before him: Sugar Ray Robinson, and even him, I wouldn't venture to say he was THE greatest.
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