Should I take German or Russian?

I speak, read and write both. Take Russian. Because German and English share roots, you can pick a reasonable quantity of German up relatively easily if you travel there, but Russian demands real study. The alphabet will be second nature within a month, it simply isn't an issue, but the noun declensions and verb conjugations are quite unfamiliar (though a bit less so if you've done any Latin). Russian is a fabulous language and a wonderful challenge. Go for it!