Theres a lot of great fights for Franklin at 185, Cote being one of them, Nate, Akiyama, Bisping, and others. If Franklin dropped back down to 185, he would definitely be the 2nd ranked person in no time, as the only MW giving him trouble would be Belfort, but I think Franklin could take him in a rematch.
Franklin at LHW isn't a good idea. While thats where he wants to be, I think he'd struggle against a lot of the larger and very heavy handed guys. Rua, Rampage, Evans, and Nog would give him a lot of trouble. But I have no doubt that he could beat Couture, Forrest, Vera, and most of the mid carders.
And, Cote would get smashed by Franklin