My best experience (b/c really, I have no other type ) was on a JAL 747. Why you ask? B/c at that time (don't know about now), the upstairs was configured as Y! It was great... smaller cabin space, less people, yet with its own galley and lavs. And Row 65 was an exit row... on one leg I just spread out a blanket and slept on the floor, there was so much room.