In terms of post game content, which game has the more challenging battles?
Not entirely sure. I know for a fact that FFXII's post game battles rely on four things. 1) Abuse of the game's flawed ATB/Query system to shut down everything but an endless barrage of physical attacks, 2) an ability that grants complete immunity for a sizable chunk of time spammed immediately after the previous casting wears off, 3) abilities that completely annihilate your party's MP, and 4) Milleons of
Toops HP (with a damage limit of 9999 still rigorously enforced). Occasionally you'll run into issue number 5 which involves Milleons of Toops (mostly hoards of Zombies and the like), but that's not exactly post game content.
Wow this sounds really.. not very fun. If I ever replay the game I don,t think I will bother with that stuff.
I am around level 60 in Xenoblade, and its still pretty exciting to see those crazy high level monsters. Will be interesting to see if I can ever take them down. The fact that I am not much of a gem crafter makes me skeptical.