1. Nine Himself
Christopher Ecclestons portrayal of the Doctor was so different to what we have seen since that it really is a standout. He was fiery, angry - he carried so much pent-up rage over losing his people in the Time War that he was at times irrational and unforgiving (and this was particularly great for older audiences who like a bit of the darkness and grit). The Ninth Doctor developed as a character throughout the series, however; guided by Rose (especially after Dalek), he became more sympathetic and more human, despite the fact that he was obviously alien. He was also a little bit like a child, which seemed fitting for the reboot of the series - so enthusiastic about everything, exclaiming fantastic! at the first sign of something pleasing. And he seemed to delight in showing Rose a whole new world; showing her that humans are important, that everyone matters in some way. Nine really established the foundations of the Doctors character and his development for the next two incarnations - and hopefully for the twelfth incarnation as well.