I have had so many great moments, but I would have to say that dancing the Swan in 'Swan Lake' was such a unique and passionate experience for me. It was such bloody hard work, even at that very early age, that I would not want to try to replicate it again now.
I believe that if creative people are open and generous enough when working with each other, a lot more can be learned and achieved by both parties. That's what it's all about, trying to produce the best work possible on any given project.