Without a multiple choice poll I can't vote honestly.
Troughton, Pertwee, Davison, and McCoy were all excellent in their own ways and I simply can't pick a favorite from among them. I waffle back and forth about how much I like Tom Baker. Aside from the very first episode, I don't care for William Hartnell. Colin Baker annoyed me. Paul McGann wasn't around long enough for me to have an opinion of him, and I haven't seen Christopher Eccelston yet, although he loses major points for quitting so quickly.