Tom Baker is the first Doctor I remember from watching the show as a kid, back when bits of it seemed really scary to me but I desperately wanted to see the next episode anyway, so I think he'll always be my favourite. He had some of the best companions too.
William Hartnell would be a close second. For some reason I found his crankiness really funny.
David Tennant is 'my' Doctor, and I think he'll always be my favourite. William Hartnell is a very close second. I agree that Hartnell is very funny in many stories. I think he's often overlooked when it comes to top doctors.
I'm old enough to remember being scared witless in those first episodes starring William Hartnell. Mention Dr Who, and his face immediately springs to mind. After last night's telemovie, his position as "top doctor" is reinforced for me.
Having watched since 1963, I have to say eleven twelfths of them. I love them all (but one) for different reasons. They have all brought such charm and whimsy in their own way. I loved Peter Capaldi for years and was thrilled when he got the role.