When I was a kid, I loved Asimov's Lucky Starr series. Other than that, I think I'm a bit more fond of his standalone stories like Nemesis and Nightfall. I tried reading the Foundation series and although I really liked the idea, I just never got into it. One of my favourite authors nowadays has to be Orson Scott Card. His is sort of military science fiction. I also love Elizabeth Moon's books although I do find them a bit slow at times.