Because I go back to Episode One with Dr Who, I have fond memories of William Hartnell, and his prickly characterisation of the original Doctor. I remember being amazed at his over-the-collar white hair, in 1963, you would be seen as a potential rebel for wearing your hair at a challenging length, which just added to The Doctor's appeal to a nine-year-old boy. I think Patrick Troughton runs a close second, because he played the part like a 'junior' version of the original, and the rest simply didn't match up.