1,) The x-files: well I had my period of extreme obsession. I didn't just love it, I was Mulder, it's a bit emberassing now, But it really is a good show and I still love it. Love the supernatural stuff and the humour. (Don't know if it counts as sci-fi where you live but here in Sweden it does.)
2.) Doctor Who: And yes it should be the tenth doctor. I love how he is (much like me I've heard, that's why I actually started watching it), his humour and how it's always the same but also different every time.
3.) Star Trek the Next Generation: The first sci-fi show I saw. Still love it, I really don't know why but I just love it.