Well, I've taken some time responding to this one--primarily because I'm pretty much at a loss on this matter. I seriously doubt that I've seen an adequate number of foreign films to pass judgment here, and my lack of knowledge of recent cinema is a pretty substantial lacuna in my knowledge of these matters. There are other problems as well: we just don't have time to watch all these movies, our conception of a nation's cinema is (largely) formed by the films that distributors decide are worth picking up, etc. I doubt I need to spell these things out for anyone here.
That said, it's not like I'm going to keep myself from holding forth on this matter. So here's my extremely tentative judgment on this matter: I find that the German films I've seen have been of the most consistent quality. (Bear in mind that this is a judgment concerned with German film up to the New German Cinema, and who knows when that ended exactly. Naturally, I'm ignoring the whole Nazi cinema debacle. I've seen a few things from this period, and I don't have much of a desire to revisit them anytime soon. For the most part, they didn't strike me as obviously pernicious: a lot of them were just run-of-the-mill entertainments. Still, it's hard to shake the conviction that there's something unseemly about these films.)
Why German cinema? It just strikes me that there were three strong periods of German filmmaking--the silent era, Weimar, and the New German Cinema--and good work was being done by several filmmakers in each of these periods. Plus, I realize this is probably cheating, but I'm also taking into consideration the Hollywood careers of German expatriates. So the spectacular American work of, say, Lang and Murnau gives German national cinema a boost.
I also have an affinity for the Japanese cinema. I just thought I'd add that in here--you know, just in case you find my adoration of Teutonic cinema puzzling or unjustifiable.