I think Joshua v Fury would be a lot closer on the cards than Wilder Fury, despite me making Wilder favourite in any match up against Joshua.
Wilder is the best knockout merchant in the division and that's what gives him a chance, but i can name a fair few fighters off the top of my head who have arguably been ahead of Wilder on the judges cards at the point of it being stopped, and a few of those have been very ordinary heavyweights (Fury, Ortiz, Szpilka, Washington) - there are probably more but I haven't seen all of Wilder's fights. Compare that to Joshua, there are probably only 1 or 2 occasions where you can say that (Klitschko maybe, Povetkin, Ruiz) and even then it's been close run and vs top level opponents.
The problem with Joshua Fury however is that while he is one of the best technical boxers in the heavyweight division, Joshua is still not quite in Fury's class in that respect and he seems to have lost the devastating KO power he had vs the gate keeper types once he stepped up to the top level.
I'd love to see Fury v Joshua to see what Joshua could do, but unless Fury got a bit lax as he has vs some opponents in the past, i'd struggle to see Joshua doing enough to either KO him or to win on points.