In terms of money making potential, it's Khabib, Masvidal, then Nate. Now that Conor's stock has risen again, it would be the best time for UFC to push for the Khabib rematch before Conor loses again or gets arrested for rape.
Even if Conor loses to Khabib, the Masvidal fight will still sell like hot cakes because both fighters can trash talk and sell the fight. Personally, I would like to see this one as well because they never fought each other before.
Nate trilogy isn't as hot now because he just got whipped by Masvidal. And we have already seen this fight twice.