This is one of Khabib's toughest matchups in the UFC imo, if not the toughest.
He would ragdoll Conor, and while Ferguson can compete on the ground I think he is too comfortable on his back and Khabib would not be threatened by his guard and woudl control him and win a decision.
Barboza has had his ups and downs, but he has never been simply taken down and beaten up/controlled that I can remember, his TDD is good and his insane athleticism certainly helps. The speed difference between these guys will be massive. I still favor Khabib but he will need to stay in Edson's face and in the clinch.