I'll go for English dub with no subtitles on my first playthrough for both games. This will be a new experience for me, since I never had an Xbox. I will play S2 in English for the very first time. Very excited about it, especially about listening to Corey's performance on the second game.
I've played the Japanese versions of both S1 and S2 many times so it won't be new to me but I'm definitely gonna do a Japanese audio playthrough at some point. I'd like to try out the German subtitles but as BlueMue already pointed out, the quality of German translations on console games tends to suck. Also I might stick to English subtitles with Japanese audio to create that Dreamcast vibe on S2.
For subsequent playthroughs, I think it will depend on my mood if I will play with Japanese or English dub. But if I start with either one, it will stay in that language throughout both games. I'm not the type to change the audio language in the middle of a playthrough.