Khabib should be top 5, as he absolutely dominated a very tough division of fighters, Poirer, Gaethje, McGregor, RDA, just a shame he didn't face Ferguson at his peak, and was just retiring when Oliviera was becoming a top contender, who was there left fof him to fight?
Do you mean left for him to fight now? Olives is one as you mention, Volk moving up is another. I also think a lot of the top 10 right now don't actually belong there they are just hanging on and refusing to fight down. Dariush, Fiziev, Gamrot, Tsarukyan, Turner, Ismagulov, Guram, Alvarez, Topuria would all give him something to think about.
Lightweight has so many killers! by far the best division.