US: Hilary Clinton
Germany: Merkel, but she is retiring at the 2017 election later in the year
France: François Fillon, but I must say thinks are pretty unclear (Copé, Sarkozy, Hollande are possible, Le Pen if things get ugly for PS and UMP explodes since then).
UK: Ed Milibrand
Canada: Justin Trudeau, ugh
Australia: Abbott (but he might be victim of a leadership spill or just lose to Labor in 2016)
I would change 3 things.
France would be Copé.
Australia would be Shorten.
Germany would be Van der Leyden (since Merkel would have retired at 2017 election).