At his prime, he could damn near beat anyone and everyone without 160-175, but the problem is that he either didn't stay long enough at 160 & 168 and wasn't really offered any particular great fighters at 175. He nowhere near top 10 middleweight even though he beat the stuffing out of some of the top 5, A case can be made for him at 168 to be a top 10, maybe top 5 in a relatively young and weak division, but he isn't taking Joe Cal's mantle. And light heavyweight? He's no Archie Moore, Michael Spinks, Ezzard Charles. He's more or less on the lower end of the top 10.
But he has weightclass transcending athletic ability and talent. Pacquiao is not considered a GREAT fighter, but you wouldn't call him the greatest featherweight, lightweight, or welterweight, would ya? No, you wouldn't. So defining his greatness in comparison to the greats in the respective weightclasses he visited is not fair. He HAD that weight transcending ability.
However, it is quite unfortunate in that when he fell, he fell hard and quick. After getting obliterated once, he was never the save again. But when he was at his peak, when his reflexes are hair sensitive, he was an extraordinary fighter capable of making the very good opponents look like they don't belong in the ring with him (James Toney). I think because such a dramatic difference from pre-tarver and post-tarver Jones, I believe 20-30 years from now, most will ignore the later half of his career and respect him at his peak. From that perspective, most will consider him a great fighter, one of the best of his generation, and one of if not the greatest pure athletic talent fighter to ever laced them up.