One option that people haven't discussed (not to diss their options) is to take D&D and simplify it and add some more narrativist houserules. Which could be more work, but depending on your system mastery might be able to get you closer to what you want. Or not, it would be a lot of work and the other systems are pretty much ready to go. Just depends on your preferences. But that's closer to D&D than Fate or Dungeon World would be, although again it would be more work, and possibly not far enough in the narrative rules direction.