The following is a list compiled on the ffxiv sub-reddit. It has a lot of things that couple use improvement to make the game really shine. Some are more important than others, depending who you are.
Since the list is pretty comprehensive, and changing, I'll just link to it. Kudos to toweler for compiling it.
http://www.reddit.com/r/ffxiv/commen...e_can_make_it/