Tom Baker gets my vote for the best classic Doctor. I never really liked Pertwee, who only gets kept off the bottom slot by Colin Baker.
Sylvester McCoy probably gets most intelligent Doctor in the classic set. But all these impressions are entirely a function of how old I was at the time.
Having rewatched what I could a few years ago, Colin Baker was a lot better than I remember him.
I suppose Tennant wins the newer set, although he did start more or less knowing absolutely everything that happened in time and space, and physics, which became tedious, and the Rose Tyler love affair I found awful, so then it's difficult. Eccleston or Capaldi I think. And I have enjoyed Whittaker a great deal, although I currently have problems getting hold of it, not having access to the BBC or Iplayer.