I like both versions of the Tower of Bab-il and the Tower of Zot because there is something oddly relaxing about the technological look they have.

I also love the last dungeon because while the music is adventurous, the layout and look carries a menacing vibe to it. The last few crystal rooms have a concrete feeling of finality to them also. On top of that, "Within the Giant" is playing which is one of my favorite FF tracks hands down.