Well, not day 3 exactly. But... am I bovvered?
As to the question - of course, our impossible, incorrigible Captain Jack Harkness (aka John Barrowman=)))). The man with the most contagious smile I know. And I won't forgive them if they don't bring him back for the anniversary. He absolutely must meet River Song. The Doctor owes him at least a kiss after the Children of Earth.