This thread isn't about the GOAT. It also isn't about PEDs. It's about technique.
We have to seriously consider that many fighters were and are on PEDs. Not all of them string boxing, wrestling, kickboxing,and submission fighting together seamlessly in a way that transcends the sport. To me, whether they do so fairly is irrelevant. It's a conversation for another type of discussion. I'm talking about pure aesthetics. Khabib, for example, would never be on this list because while his wrestling is phenomenal, his striking leaves a lot to be desired and is mostly predicated on toughness. His submission fighting is also suspect as he makes fairly elementary mistakes when transitioning between submissions that are usually covered up by his ability to win every scramble with his wrestling and his relentless pressure.
DJ's opposition doesn't really matter as much because much like GSP and Jones it was skill that made everyone else look like amateurs. In fights with other people in their weight class, DJ's opponents rarely looked as bad as they did against him. Can we really say guys like Josh Koscheck and Carlos Condit were that much better than Kyoji Horiguchi and Ricardo Lamas? Not convincingly, imo. 125 was just poorly marketed and didn't have a ton of competitors in the UFC.
One person I saw mentioned that I think there is an argument for is prime BJ, but I feel like he's done so much damage to his legacy since the Edgar fights that it's hard to evaluate him fairly.