I haven't seen "O" yet, but KA is my favorite Cirque du Soleil show so far! Set to an Asian theme, beautiful imagery and special effects, amazing acrobatics and stunts, combined with a touching storyline is what made me fall in love with this production! The theater itself is amazing, as are the sets, props, and costumes for each scene. My favorite part of the show was the inverted stage battle scene in which the performers fought vertically, up and down! I would see KA again, it was worth it!