Hrm, i'll try to jump on the bandwagon, for the people i can make an opinion on. =.=
USA : Obama = I'll be waiting for the end to give the grade, the term isn't over until it's over. =/ I had high expextations, i think he "could" still pull it off, but he should get in high gear.
Bush = F , i guess that shouldn't come out as a suprise, seeing all the incompetent things he's done. -.-
Clinton = C , i know little of him, from what i could remember, but i know that during his time, the USA didn't suffer economicly like it did with Bush jr. . That and even today, the guy is still reknowned worldwide. <.<
Canada : Harper = D , his policies are rather harsh, partisanship is ruining attempts at finding a joint solution to the country's problems. Also acts as if he had a majority when he's got a minority. Nonetheless, he is crafty and has done some smart politic decisions (not to say they're good, mind you).
Paul Martin = D + , For all i knew about the guy (which amounts to less than i'd want) he is still less worse than Harper in many regards. Still didn't leave without a few skeletons in his closet.
France : Sarkozy = D+ , he had a good vibe going at the start, even though i voted for the socialists (Fine, sue me! ><), but he seems little more than a clown for the french media -.- Nonetheless, he still suprises me (sometimes) with his speeches (in a somewhat good way). His future is currently uncertain, but at the very least he got me slightly more interested in french politics. =/
Jacques Chirac = D -, from what i recall, France didn't exactly stood out or did anything worth noting while he was in place...
That should be about it -.- Keep in mind my information network might not be as wide as yours. And that it's generally hard to get the big picture, along with the feel of the times.