re: Who knows?
"I know that given a choice between John F. Kennedy and ANY of the current crop of Democrats, I would cheerfully vote for Kennedy. Would probably vote for him over McCain, too."
That's not saying much, it's a bit like saying you would vote for Reagan.
Better question which Dem is most like John F. Kennedy?
I would guess Obama, but he's too young for '08- just like JFK was too young.