Just the power to know all that there is. In that way, you could create anything to do everything, and if not possible with current technology, you would know how to create the technology that can.
Time and space manipulation because you need both to function well. Don't want to go back in time and find you're not standing on Earth lol. But I'd simply rewind back to the Dinosaurs and Egypt, etc. Oh and especially the early humans. Wouldn't be able to understand any of their language and would probably have to keep my distance but it'd be cool I think. Then I'd go far into the future to meet Aliens with higher or equal to human sentience and intelligence... Yes I'm a nerd lol