Okay! When you consider someone a good World Leader, you need to look beyond the popularity polls.
A War can turn a so-so Commander In Chief into a hero (like making a silk purse from a sow's ear).
Papa Bush had ratings similar to Dubya during Desert Storm, but when it came time to choose the next President, Senior Bush was left holding the bag.
Sorry, but in the long run, I do not think the Bush half of this Fantasy Ticket has the staying power to be anything more than be a cheerleader for America. Remove the script and he starts to babble and trip on his own words. The fact that we're in a war has caused everyone to not question his abilities, because they would be told to rally behind the President or you are 21 Century version of the Commie! (Yay , I got to Bushwack!)
I don't know much about Blair, though he has a silver tongue, from what I hear from our British friends here, there is more below the surface.
At this moment in history there is no one who can or should run this World.