1. Armor textures (especially just those really terribly low-grade outliers, often right in the middle of a chestpiece or whatnot -- Crystal-patched Exarch, Hien, etc.)
  2. Hair textures
  3. The Luminous Engine issues with edge-drawing on shapes while drawing closer/further that cause said edges to look like they're flickering/sweeping/strobbing (my largest peeve)
  4. Grass perceived poly count / general appearance
  5. DX11 flickering issues from water transparencies/reflections
  6. Ground textures
  7. A subtler level of action VFX that still makes it obvious what's been cast/used without obscuring the target it's been cast/used upon...

Those are the essentials, imo. Plenty more to cover thereafter, though, such as flora physics, better normal mapping over terrain of unique lighting effects from rain and snow (see Edge of Eternity for good, low-cost examples), better passing cloud shadows, and finer procedures for drawing in objects that don't make them seem to spawn in constantly at a set range regardless of their obviousness, etc.