Lu Chen in 1998 Nagano without a doubt! One of the highlights of any Olympics IMO.
Michelle in SLC would be second for me. To me, she started off stiff and slow, but after the fall on the flip, she just let go and performed the rest of the program with emotion. A lesser skater would have just gaven up and make more errors, but not Michelle. Her attitude after the performance on the ice and in the Kiss n' cry showed her true character.