Well, we’ve had favourite Even, Odd, Prime, Classic, 2005+, and Parody Doctors, so clearly this is the next logical option!
A perfect number is one where its factors (excluding the number) can be added together to make the number itself. For example, 1 + 2 + 4 + 7 + 14 = 28, which is perfect!
The 28th Doctor is propably the doctor where I will be showrunner or at least common writer, thus having most of my favorite Tropes, turning him into my favorite.