Omnipotence (similar to the ability to touch a book and known the contents instantly, but in this case for all knowledge past, present, future) is the most powerful thing I've ever been able to think of. That really allows you to do anything. If something is at all possible, you know how to do it. You can prevent death, control everyone around you, know what everyone's thinking and the secrets of the universe. You'd instantly become a god with knowledge. If someone had this power the Earth would quickly either turn into paradise or possibly a horrifying god-emperor dictatorship.
Super speed is my #2, for similar reasons. If I can learn to how to do almostly instantly, would easily become rich and powerful, etc.
Basically absorbing knowledge as fast as possible is super important! Flying and strength are just about the most restrictive superpowers!