Eccleston was great, but sometimes he was pulled down too much by his deeds about the Daleks and the Time Lords.
I absolutely loved Tennant. Almost everything about him was great, though he could be a little bit too self confident. Well, in the end this hubris was what brought him to his downfall. Keyword:
I am the Time Lord Victorious
I never really liked Smith. Partly that's not his fault, but Moffat's. I very much liked the style of the new series, brought in by Russell T. Davies. Moffat's style seems too polished to me at times. But even with that aside, Smith was always so hyper, but still so clumsy, especially in regard to humans.
I look forward to Capaldi. He seems a bit more dark, maybe a bit more "Eccleston-ian". It'd be good to have a doctor with a dash of cynicism again.