Mo and Mousasi have a ways to go before they could be in the hunt. Both have strengths but its the weakness's that will hold them back.
Machida would be able to take Mousasi down at will and Mo can be beat in any number of ways. Jackson is packing a lot of power and would destroy a fighter that can't slip and move, mo may look flashy but his stand up is too underdeveloped for a top fighter.
Barnett should be able to out grapple Cormier, I'm not sold on him being able to push Barnett around on the ground and my bet would be he'll get tapped if he takes Josh down. I might be considered biased though.