I like them both, but I chose the 7mm-08. In Kentucky, my state of residence, they have a minimum .277 caliber requirement for elk. Although I believe that with good shot placement, the 6.5 would do the job, it would not be legal in my state in the event I get drawn for the elusive Kentucky elk tag.
Good luck with that Elk draw. I’ve had one cow draw since the lottery started, and my son has never been drawn.