Both version are good and bad, I wish they had kept the good from v1.0
I would go back for the better movement motions (especially Lalafell!!!! I want my cute Lalafell demeanour back!! :(),
the original armoury system (being able to use all skills and super-personalize your character),
the vastness of the maps (the world felt really big, not like now),
the various detection from monsters, the various leves mechanics we had (more than just kill this and that),
the mini-games for gathering (a million times better than the current point and click for simpletons)
and the feeling of danger when walking in the world (mobs level 99!).
However, I would really miss jumping (even though it is flawed in ARR -- only two: walking or running jumps, no standing forward jumps),
the better character creator,
the areas are more alive in ARR (world objects and towns are properly represented),
the interesting story,
my magitek armor from FFVI,
chat bubbles (only NPC though... http://forum.square-enix.com/ffxiv/i...lies/frown.png) and the better UI.