I was born 1980, so the first Doctor to have an impact on me was Sylvester McCoy. I've since watched the entirety of the McCoy years and have to say they were all a bit pants, but they paved the way for my love for the show.
I also used to love the Pete Cushing film back in the day.
The current series though is the best by such a long shot, the BBC have really pulled out all the stops. Its also nice that each episode is self-contained rather than an individual story spread over 4 episiodes.
My favourite Doctor? David Tennant by a long shot. He's just perfect at it, you can see how much he enjoys it. For the old boys, Tom Baker gets my vote, mostly because my gran knitted me one of his ridiculously long scarves when I was young.
STELLA S: There were 2 bakers, Colin and Tom. Tom had a long coat with very long stripey scarf, Colin had the campest kit ever - all yellow with red question marks, and his umbrella handle was a question mark too.