For me, this is a difficult question because I have yet to see a ballerina who masters both roles. Makarova was a model Odette: she lived and breathed the part, possessing all the vulnerability, pathos and lyricism required, as well as the supple upper body and liquid arms that made her Odette unforgettable. I think she was a good, but not great Odile. She was seductive but just not evil enough for my tastes.
The best Odile I've seen hands down is Maya Plisetskaya. She was seductive, riveting, technically brilliant and eclipsed all the princesses at the ball. She was deliciously evil and I'll never forget when she reveals herself to Siegfried at the end of Act III she laughed maniacally at him and pushed him away contemptuously when he still thought she was Odette.
This should be a good thread and I look forward to reading everyone's opinions on O & O.