For me, Doctor Who will always be Peter Davison.
It’s a matter of age. I was just old enough to be watching Doctor Who during his tenure, and to be traumatised by his near-death and regeneration at the end of The Caves of Androzani. As a little kid, this charming, energetic young man was everything I wanted to be. The fact that he beat alien menaces without resorting to violence really clinched it.

Of course I enjoyed Colin Baker, for all that I know now that he was controversial. And I loved Sylvester McCoy, with his erratic energy and weird, dark plotlines. Berty Bassett still gives me the creeps. I watched the older doctors on video, and took a particular liking to Jon Pertwee, for reasons I can’t even remember.
I was gutted about the McGann mess, for all the flare he brought to the role, and then immensely releaved when the RTD revival got it right. I’ve enjoyed Eccleston, Tennant, Smith and now Hurt, and I cannot wait to see Capaldi take on the big blue box. These days, the Doctor just seems to get better and better.
But for me, and I suspect many others, the appeal of Doctor Who isn’t in the quality of the show, which has swung wildly about over time. It’s in my emotional attachment. And that lies forever with the fifth doctor.