Dear Mr Moffat...
I know you're busily searching for the next Doctor, and that you must therefore be very busy. Fortunately, I can help you solve that problem for you. Clearly, and for reasons that shall soon become obvious, I am precisely the right person to be the next Doctor.
"But why?", I hear you ask. Well, allow me to present my case. I'm sure you'll find the logic is irrefutable...
Really, it's a simply matter of elimination. See, until recently, every single Doctor has been older than I am. But that ended with Matt Smith, where for the first time the actor to portray our hero was younger than I am. There is now only one option that has not been explored: the next Doctor must be exactly the same age as I am! It's the only possibility.
Now, of course, you could try seeking out an actor who happens to be exactly the same age as I am. I suppose that would make sense. But why bother? Why not just go straight to the source, and pick the person who most undeniably fills that criterion?
Plus, of course, my sense of whimsy is almost legendary amongst all three readers of my blog (although, granted, one of these is my wife, who is practically required to read it and say "yes dear" at appropriate intervals and with rising levels of long-sufferingness, so she might not count). And I can easily carry on some of the trends started by Mr Smith, as every new Doctor has incorporated mannerisms of the last - I can supply my own bow tie; indeed, I can supply either a clip-on as sported by Mr Smith or a tied one... though my ability to actually tie the latter is best described as comical. Likewise, Mr Smith had a fez; I've always wanted a fez, because fezzes (fezes? fezi?) are cool.
See? My logic is quite simply unassailable. So, when can I start?
#20: "The Ionian Mission", by Patrick O'Brian
#21: "Treason's Harbour", by Patrick O'Brian