I'm doing bio, chem, maths and geography this year and hopefully applying for medicine. Imo geography content isn't too hard and I'm guessing has less to revise than German (I've only done 4 topics). I'd go for the one that's gonna be easier to get an A in, as i think both are equally respected (however German May have more of a wow factor). But it's completely down to you.
P.s: I'd only take further maths if you really enjoy maths as most unis don't count it as a desperate a level. But again it's up to you.
Good luck in your exams and applying