Prime Anderson Silva had the biggest aura of invincibility. If you stayed on the feet he would knock you out. If you took him down he would submit you. He had losses before and after his prime, but in his prime he was unbeatable. Khabib will always be known as the most dominant because of his grappling, but he is a one trick pony in that regard. It is however the best trick in the sport. If Khabib takes you down it's over. You can not beat him if he gets you to the ground. If he can't get you to the ground then he could be in trouble and that's why he didn't have the biggest "aura of invincibility."
Everyone that Khabib faced thought that they can prevent the takedown and they were dead wrong. They had confidence though, so the aura wasn't there. He is and will be the most dominant, but the thought remains that you can beat him if you can stop the takedown. The thought is wrong though, because only one has stopped the takedown and Khabib arguably lost that fight.