sonoko
Russian is not, in fact, as hard as many believe. But I feel like I'm not one to judge it; I've spoken it since birth. But even in school, I noticed that Russian grammar was less difficult for me than Ukrainian, despite having learned Russian grammar on my own. However, even for native speakers perfective/imperfective splits are pain on exams and tests.
I also think that gender is a huge problem for people learning Russian, especially those whose mother tongue is English. At least, that's how I think. Combining this with six cases can cause trouble and confusion while learning. Correct me if I'm wrong, but I think it might be difficult to learners.
I agree that German is likely the correct language to learn, since many countries speak it. But there's will be a problem with dialect, obviously. Even within Germany this is a disaster. I heard Schwäbisch dialect and then Bavarian, comparing them to each other I've come to conclusion that Schwäbisch is "unique" but understandable, but on the other hand, we have Bavarian, which sounds to me more like Spanish, especially when they are shooting, as if from a machine gun, with words. The same applies to different countries. But even knowing Hochdeutsch would make your trips to German-speaking countries much more comfortable.
Picking the German language, you sacrifice a lot of Russian media, which includes tons awesome things. Many Soviet Union films are pure classics of cinematography, totally worth the time spent learning Russian. The same applies to books; however, the German language provides you with classics of literature as well, mostly philosophy.
I highly recommend you to get familiar with some classics of Russian (or Soviet) cinematography in English if you end up picking German to learn.