I have liked most FF airship themes, and disliked many...Anyway, my favorite are

FF3- The invincable(SP?) airship music

FF9- hilgany(or whatever the ### its called, the airship you get on the third disc before you head to Terra)

FF4- Regular Airship music(not the whale, just the regular ones you use when you have cid in your party)
even though it's only about 21 second repeat, this is one of my favorite FF musics.