Now that I think about it, my answer in each category is just about the same. FF6 as more involved and deeper, but at the same time a lot broader. CT used it's more limited scope to deliver a lot tighter experience. If I was to break it down by each element then FF6 would probably win the balance of the categories, but CT did a better job of putting all it's elements together and hence had a better overall gameplay experience.

Which is why I don't like thinking about the different elements of a game in isolation.