5.) Kingdom Hearts
Kingdom Hearts may not be as old as Final Fantasy, but its popularity and quality isn't something people should doubt. The first two main games were exclusively released on PlayStation 2. However, the third one will now be available on the Xbox One and the PlayStation 4.
I think Sony would be more inclined to court this franchise, but it would be beneficial for either side in my opinion. It also appeals to wide audience since it's a mash-up that includes Disney characters as well.