I'd also choose JFK. First I'd ask him how it felt to be assassinated after fighting off what is supposed to be an endless horde of zombies. Then I'd show him Black Ops. Winning.
Since it does not specify if the president or prime minister has to be alive, I would choose George Washington, the first President of the United States.
I don't know whom I'd like to meet, but I know whom I don't want to meet - it's russian president, prime minister or other people from government on the roads, cuz of them we have enormous trafic jams here.