Well, according to China's men's singles coach Xia Xuanze on video, he said Lee Hyun Il has the best footwork if I understand it correctly. http://v.youku.com/v_show/id_XMjMxNTYzMTMy.html
Xia didn't go into direct comparisons, but he said LHI seems to glide on the court. Xia also said LCW has very good footwork, the way he puts it, both LHI and LCW has better footwork than LD. But footwork is only part of the game, we all know who is the better player out of the three.
I won't argue with the names put in so far. But having just watched the video of his game against Chen Long in the Asian Games, I'd say that Son Wan Ho has some pretty nice footwork. https://www.youtube.com/watch?v=wDTpHm9YIXc
imho, i think the following people have the best footworks (in this order) in the past 2 Olympics cycles: LD, LXR, LHI, Zhang Ning, LCW and Peter Gade.