6. Scottish
Peter Capaldi is from Glasgow. Glasgow is in Scotland, which ispoliticallypart of Britain. The Doctor has to be British; and technically, Scotland fits the bill. Indeed, I have heard that the showrunners (running with this similar mindset) had considered allowing David Tennant to display his own Scottish dialect but had decided upon the safer avenue of having him assume the RP dialect due to previous complaints regarding Christopher Eccleston's Northern slant. Now, however, we've had two Doctors in a row who spoke in RP, and I think it's time for something new. Sylvester McCoy's Doctor spoke with some Scottish flavour, if you recall, so it's not unheard of. I feel a Scottish accent may reemphasize (especially for the growing American audience) the alien-ness of the Doctor, an aspect of his character that has been forgotten somewhat in the past few series.