I'd personally like a whole new world and story.

The reason games like ff6-10 were such classics for me is they each were so different. Different world, characters, technologies, feel, but still retaining that Final Fantasy core. I know everyone has their favorites and dislikes from the older games, but I really enjoyed them all, each was an entirely new adventure.

A new FF MMO should be the same. New story, new combat, new systems. I'd like to see the developers being brave again. It's sad seeing the company that once took the lead on graphics, storytelling and innovation, now stuck with an old spaghetti code 1-2-3 casual game and the same tired safe formula for years.