Farooq should have been world champ, King of the Ring 1997 he was so hot and they should have pulled the trigger.
Other than that, maybe an R-Truth transitional reign? Lashley probably would have been if Hayes didn't make him quit, they were high on him. Booker T clearly should have beaten Trips. The only other person in that list Vince posted that I think could even have gotten close would have been MVP.
Obviously Henry was WHC, but I don't think he was ever good enough for the main gold. Not a fan of his at all, but credit where it's due, guy busted his ass for over a decade.
Love what I've seen of Xavier so far. Guy can talk and he's had good matches in NXT. Let's see where it goes from here. Think the guy who's going to benefit most though is Kofi. Man, he's basically been the same guy since he started.
MVP and Lashley both left more or less on their own terms and both would have very likely been at least WHC, with Lashley probably getting the WWE belt at some point.