As one of the handful of girls who worked with both of those dance geniuses, I think I can give an honest comparison. In my opinion, Kelly is the more inventive choreographer of the two. Astaire, with Hermes Pan's help, creates fabulous numbers - for himself and his partner. But Kelly can create an entire number for somebody else... I think, however, that Astaire's coordination is better than Kelly's... his sense of rhythm is uncanny. Kelly, on the other hand, is the stronger of the two. When he lifts you, he lifts you!... To sum it up, I'd say they were the two greatest dancing personalities who were ever on screen. But it's like comparing apples and oranges. They're both delicious.