Hello, rankings, so glad to see you...
1. Matt Smith
2. Tom Baker
3. Peter Capaldi
4. Sylvester McCoy
5. David Tennant
6. Patrick Troughton
7. Jon Pertwee
8. Christopher Eccleston
9. Colin Baker
10. Peter Davidson
11. Paul McGann
12. William Hartnell
I really like McCoy, even though I don't care for most of his first season (with the exception of Paradise Towers), but his second and third season are of amazing quality. Remenbrance of the Daleks, The Happiness Patrol, The Greatest Show in the Galaxy, Ghost Light, The Curse of Fenric... all those are among some of my very favourite Classic Who episodes.
McGann is really only so low because he's only really in the movie, and that one, while McGann is quite good, is just so atrociously written that I never really connected with his Doctor - going with TV appearances, at least. I read some of the BBC-published Eighth Doctor Adventures, and they are really quite interesting.
Never cared about William Hartnell. I'm not quite sure what it is, but I just never liked his portrayal of the Doctor, though I like some of his serials - The Time Meddler, for instance, is really quite good.