i like both... but if i had to choose, yak n yeti. partially because ak doesn't have good food options and epcot does... so it makes it easier that way. i have a recent review of yak n yeti up on the review boards
I have been to both but would pick Yak & Yeti. It's always one of the best meals of our trips. Nine Dragons is good but they do not have the amazing friend wonton dessert. I also prefer the atmosphere of Yak & Yeti.