IMO Jones wouldnt have beaten Barnett, but Cormier would handle all of Jones opponents.
This, if Jones' opponents fought Cormier at HW. IMO Daniel is a natural HW, at least at this point in his life, and I think his physical talents would be nullified if he fought seasoned LHW's at their weight.
Jones vs Cormier at HW? Cormier all day for me. The only guys I would not be confident in him against right now are JDS and Reem.
JDS because yes he terminates everyone, but the key here is that he beat a very similar fighter in Velasquez. Cormier has better hands than Velasquez IMO but JDS is still well ahead and should find an opening to time. Great grappling base for Dan of course, but look at the variety of fighters who have been forced to stand. JDS favourite.
Reem is a danger to Cormier for his clinch work. He's devastating in a stationary clinch, against the fence, and most importantly when being pushed backwards. If you're going to shoot on him, make sure not to leave enough room for knees. Dan has the hands to set Reem up, Reem does have a really good sprawl too. I'd say Cormier can weather the storm and turn the fight around later, when his fitness overtakes Reem's. He definitely needs to be careful early on though.
Otherwise, I like Cormier against anyone right now, awesome fighter.