Lord Aizen and Lord Lelouch are two of greatest genius's and tacticians in anime history. That being said Lelouch has failed multiple times in battle, however the only time Aizen failed was the very last fight against Ichigo and that was because of a unpredictable anomaly. So I am going with Aizen for planning and tactics.
For manipulation, I have to go with Aizen as well. Though Lelouch fooled almost everyone around him, Aizen had everyone fooled about his true attentions. Even Gin didn't know everything Aizen was planning and once you usefulness was fulfilled he disposes of you, while Lelouch doesn't intentionally through away his friends or subordinates.