My first exposure to Doctor Who was a couple of unconnected Saturday Mornings when I happened to wake up before the cartoons started. There was this strange show that I didn't quite understand. They were Pertwee episodes from the middles of two different stories. I was mildly curious, but it was shown too early in the morning for me to become attached.
A few years later, on another station, during the afternoons, the Tom Baker shows were shown. To these I became a fan. I never got into any of the Doctors that followed, however (especially the younger, handsomer ones who always seemed to me the antithesis of what the character should be).
It seemed to me that Tom Baker would always be the definitive Doctor for me, and possibly the one and only.
Yet, when I later discovered reruns of the earlier Doctors, I was very impressed by Jon Pertwee's take. He added action-hero elements to his Doctor, and kept the humor to a minimum, which added enormous suspense to his stories. He made the Doctor into a sci-fi Sherlock Holmes, of sorts. I also liked that so many of his adventures took place on Earth. Many fans consider this a drawback, but in Pertwee's view: "I think it's infinately more frightening to find a Yeti sitting in your loo in Tooting Bec, or the Daleks streaming over Westminster bridge than it is to find them on an alien planet!" I agree with his assessment.
These past few weeks, a local station has been replaying his series, and I'm even more impressed by the work than I was before. While I did enjoy the breezy charm of Tom Baker immensely, for me the best Doctor is Jon Pertwee.