I will definitely be playing with the Japanese voices. I won't even try out the German voices because I know they will suck. Germany is usually very good at dubbing. Much better than Americans for example because we dub literally every foreign film or series for our market. Like in Japan, voice actors are in big demand here and they can make a good living from it. But video games, especially Japanese ones, do mostly get the crappy anime series treating. They are miles away from the quality that foreign movies or series are dubbed in. :/
From a French who went to Gamescom and heard German voices, they are quite good (even if it's sound strange, because it's not my mother tongue)