^Agree with the guys saying Diaz/Sanchez II would be great. Their first fight was so amazingly awesome...but I think Diego is going down to 155.
But I also believe Diaz's TDD is better than it used to be, as is his BJJ. I think he would take Kos but Fitch is a monster so IDK who would win that. The thing about Diaz is he won't wear down like most guys who fight Fitch.