If you could choose any person from history to be your imaginary friend, who would it be and why?

Albert Einstein. It's my belief that had he lived in our world for a day, he would have invented gadgets that would speed up our lives. He would have also worked on the cure for cancer, diabetes and AIDS during his spare time. But the most important part is he would have taught me a lot of things. Questions like "What is the meaning of life?", "How did life started?" etc would have been answered by him. I would have also asked him to teach me the laws of physics.