Susano is by far my favorite. I love the fight, the OST, the boss design - Everything!

Baelsar's Wall on the other hand... I still end up in there from time to time with a group of complete new people and it is a pain to get through the dungeon and especially the Griffin. As I play healer most of the time I can't really burn down the boss with my Stone and when the DPS is low, things can get really difficult.